Laboratory Animals (1975) 9, 193-196.
193
A 'SILENT' FIRE ALARM by G. CLOUGH
and J. A. L. FASHAM
Medical Research Council Laboratory Animals Centre, Woodmansterne Road, Carshalton, SM54EF Various alarm systems use. devices such as bells, hooters and klaxons to alert personnel to fire or other hazards. In order to ensure their satisfactory performance should an emergency arise they must be tested regularly. In any institution in which animals are used such loud noises, occurring at infrequent and irregular intervals, can have disturbing and stressful effects on the animals (Pfaff, 1974). Electric fire bells have been shown to have adverse effects on the reproductive processes of both rats and rabbits (Zondek, 1959; Zondek & Tamari, 1958, 1960, 1964a, 1964b). Such occasional sharp, loud noises, can also act as a stimulus for audiogenic seizures or may act as a 'primer' for such a seizure on some future occasion (Henry, 1967; Iturrian & Fink, 1968; Lane-Petter, .1963). A single 30 s fire bell test in an animal house can result in changes in maternal behaviour and a depression in lactation in some species (D'Sousa & Martin, 1974). Other examples of physiological responses to noise include histological changes in the median lobe of the rat pituitary (Werner, 1959), hyperplasia of adrenals and a reduction in the lymphatic tissue of the thymus gland of the guinea-pig (Anthony & Harclerode, 1959), an alteration of the circulating eosinophil level in mice (Anthony, 1955) and even a reduction in total bodyweight of some primates (Sackler, Weltman, Bradshaw & Jurtshuk, 1959). The results of other studies indicate that auditory stimuli can induce regressive changes in various species resembling those produced by other stressful stimuli (Pfaff, 1974; Warfield, 1973; Zondek & Tamari, 1967). It is now known that there is considerable interspecific variation in sensitivity to different sound frequencies (~arfield, 1973). Fig. 1 indicates diagrammatically the reported frequency ranges to which the species shown are known to respond, together with an indication of those frequencies to which each species is most sensitive. From this it can be seen, for example, that mice are insensitive to sounds below 1 k Hz (the frequency of the Greenwich meantime 'pips' on the radio). In the case of rats, Crowley, Hepp-Reymond, Tabowitz & Palin (1965) have recorded cochlear microphonic potentials from both adults and infants to signals as low as 100 Hz; they also found, however, that the threshold increased rapidly below -1 kHz and that the rats' most sensitive frequency range is from 35-40 kHz.
Downloaded from lan.sagepub.com at Queen's University on March 6, 2015
G. CLOUGH
194
100 000
AND
J. A. L. FASHAM
C
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A
F
G .........
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"
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10 Fig. 1. Reported hearing range (stippled) and most sensitive frequency range (black) of some laboratory mammals, with sound frequency output of the 'silent' fire alarm. References: A Mikaelian & Ruben (1964), Mikaelian, Alford & Ruben (1965); B Finck & Goehl (1968), Finck & Sofouglu (1966); C Dice & Barto (1952), Ralls (1967); D Finck & Goehl (1968); Finck & Sofouglu (1966); E Crowley, Hepp-Reymond, Tabowitz & Palin (1965), Gourevitch & Hack (1966); F Wever (1959); G Wever (1959), Price (1963); H Robinson & Dadson (1956); J Fasham & Clough (1975).
Bearing these facts in mind it was decided to construct a device which produced a loud, low frequency noise suitable for use as an alarm signal for human beings whilst at the same time being below the frequency threshold (or at least outside the most sensitive frequency range) of those species commonly used as laboratory animals, in particular the rat and mouse.
Downloaded from lan.sagepub.com at Queen's University on March 6, 2015
A 'SILENT'
FIRE
MATERIALS
AND
ALARM
195
METHODS
The device developed produces pure tones alternating between 430 and 470 Hz, and operates from a continuous or pulsating d.c. supply of nominally )4V. To ensure operation at the end of long supply lines, it is designed to operate down to 5V. The alarm has an output of 3W with a 24W supply and the supply current is 250 mAo Details of the electronic circuitry and construction are available (Fasham & Clough, 1975). In order to assess the effect of the alarm on animals, 2 behavioural tests have been used: arousal from sleep; assessment of startle response-an abrupt reflexive movement of the entire body in response to a sudden, intense sound (Landis & Hunt, 1939)-and other visual indications of auditory disturbance. RESULTS
When the alarm is switched on in an animal room-giving a sound level of 97 dBC at 450 mm-rats and mice are not awakened from sleep and, if already awake, show no startle response, ear twitching or other indication of auditory disturbance. Rabbits and guinea-pigs show little more than 'mild disturbance' at this intensity and no visually appreciable response at all when the alarm is sounded in the corridor of the animal house-the site of an existing fire bell. As far as humans are concerned, however, the noise produced by the device is intensely irritating and disturbing and the Fire Officer and other persons interested in safety on the Carshalton site have agreed that the noise is very suitable as an alarm signal. The intensity of the sound produced was selected so that each existing fire bell could be replaced by one of the new alarms. DISCUSSION
The numerous effects of noise on animals are well documented, and range from audiogenic seizures, to teratogenic effects, trauma and irreversible deafness (for discussion see Pfaff, 1974; Warfield, 1973). The increasing use of audible warning devices, together with the need for their regular testing, creates a source of disturbance to animal facilities-that is, loud noises at irregular intervals, usually interspersed with relatively long periods of comparative quietness. Pfaff (1974) has outlined some of the problems of noise in the animal house, and the device described here was produced with the specific intent of reducing one source of stress to at least some species of laboratory animal. At Carshalton, it is intended to replace all fire bells in animal areas with the 'silent'
fire alarm. REFERENCES Anthony, A. (1955). Effects of noise on eosinophil levels of audiogenic seizure susceptible and seizure resistant mice. Journal of the Acoustical Society of America 27, 1150-1153.
Downloaded from lan.sagepub.com at Queen's University on March 6, 2015
196
G. CLOUGH
AND
J. A. L. FASHAM
Anthony, A. & Harclerode, J. E. (1959). Noise stress in laboratory rodents. II. Effects of chronic noise exposures on sexual performance and reproductive function of guinea pigs. Journal of the Acoustical Society of America 31, 1437-1440. Crowley, D. E., Hepp-Reymond, M. C., Tabowitz, D. & Palin, J. (1965). Cochlear potentials in the albino rat. Journal of Auditory Research 5, 307-316. Dice, L. R. & Barto, E. (1952). Ability of mice of the genus Peromyscus to hear ultrasonic sounds. Science, New York 116, 110-111. D'Souza, F. & Martin, R. D. (1974). Maternal behaviour and the effects of stress in tree -shrews. Nature, Lond9n 251, 309-311. Fasham, J. A. L. & Clough, G. (1975). A fire alarm for laboratories and animal rooms. Electronic Engineering 47, 27-28. Finck, A. & Goehl, H. (1968). Vocal spectra and cochlear sensitivity in the Mongolian gerbil. Journal of Auditory Research 8, 63-69. Finck, A. & Sofouglu, M. (\966). Auditory sensitivity of the Mongolian gerbil. Journal of Auditory Research 6, 313-319. Gourevitch, G. & Hack, M. H. (\966). Audibility in the rat. Journal of Comparative and Physiological Phychology 62, 289-291. Henry, K. H. (1967). Audiogenic seizure susceptibility induced in C57Blj6J mice by prior auditory exposure. Science, New York 158, 938-940. Iturrian, W. B. & Fink, G. B. (1968). Effect of noise in the animal house on seizure susceptibility and growth of mice. Laboratory Animal Care 18, 557-560. Landis, C. & Hunt, W. A. (1939). The startle pal/ern. New York: Farrar. Lane-Petter, W. (1963). Animals for research. London & New York: Academic Press. Mikaelian, D.O., Alford, B. R. & Ruben, R. J. (1965). Cochlear potentials and VITI nerve action potentials in normal and genetically deaf mice. Annals of Otology, Rhinology and Laryngology 74, 146-157. Mikaelian, D. O. & Ruben, R. J. (1964). Development of hearing in the CBAjJ mouse. Acta oto-laryngologica 59, 451-461. Pfaff, J. (1974). Noise as an environmental problem in the animal house. Laboratory Animals 8,347-354. Price, G. R. (1963). Middle ear muscle activity in the rabbit. L The loss threshold. Journal of Auditory Research 3, 221-231. Ralls, K. (1967). Auditory sensitivity in mice:- Peromyscus and Mus musclilas. Animal Behaviour 15, 123-128. Robinson, D. W. & Dadson, R. S. (1956). A redetermination of the equal loudness relations for pure tones. British Journal of Applied Physics 7, 166-181. Sackler, A. M., Weltman, A. S., Bradshaw, M. & Jurtshcuk, P. Jr (1959). Endocrine changes due to auditory stress. Acta endocrinologica, Copenhagen 31, 405-418. Warfield, D. (1973). The study of hearing in animals. In Methods of animal experimentation (ed. W. I. Gay), vol. 4, chap. 2. New York & London: Academic Press. Werner, R. (\959). Influence du son sur Ie lobe intermediaire de l'hypophyse de rat. Compte rendu de I' Association des anatomistes 104, 783-788. Wever, E. G. (1959). The cochlear potentials and their relationship to hearing. Annals of Otology, Rhinology and Laryngology 68, 975-989. Zondek, B. (1959). Studies on the mechanism of the female genital function. Fertility and Sterility 10, 1-14. Zondek, B. & Tamari, I. (1958). Stimulation of the anterior pituitary function with pronounced decrease in fertility by stimulation of the auditory organs. Preliminary note. Bulletin of the Research Council of Israel Section B, 7E, 155-156. Zondek, B. & Tamari, I. (1960). Effect of audiogenic stimulation on genital function and reproduction. American Journal of Obstetrics and Gynecology 80, 1041-1048. Zondek, B. & Tamari, T. (I 964a). Effect of auditory stimulation on reproduction. IV. Experiments on deaf rats. Proceedings of the Society for Experimental Biology and Medicine 116,636-637. Zondek, B. & Tamari, I. (l964b). Effect of audiogenic stimulation on genital function and reproduction. Ill. Infertility induced by auditory stimuli prior to mating. Acta endocrinologica, Copenhagen Suppl. 90, 227-234. Zondek, B. & Tamari, I. (1967). Effects of auditory stimuli on reproduction. In The effects of external stimuli on reproduction (ed. G. E. W. Wolstenholme & M. O'Connor). Ciba Foundation Study Group 26.
Downloaded from lan.sagepub.com at Queen's University on March 6, 2015
193
A 'SILENT' FIRE ALARM by G. CLOUGH
and J. A. L. FASHAM
Medical Research Council Laboratory Animals Centre, Woodmansterne Road, Carshalton, SM54EF Various alarm systems use. devices such as bells, hooters and klaxons to alert personnel to fire or other hazards. In order to ensure their satisfactory performance should an emergency arise they must be tested regularly. In any institution in which animals are used such loud noises, occurring at infrequent and irregular intervals, can have disturbing and stressful effects on the animals (Pfaff, 1974). Electric fire bells have been shown to have adverse effects on the reproductive processes of both rats and rabbits (Zondek, 1959; Zondek & Tamari, 1958, 1960, 1964a, 1964b). Such occasional sharp, loud noises, can also act as a stimulus for audiogenic seizures or may act as a 'primer' for such a seizure on some future occasion (Henry, 1967; Iturrian & Fink, 1968; Lane-Petter, .1963). A single 30 s fire bell test in an animal house can result in changes in maternal behaviour and a depression in lactation in some species (D'Sousa & Martin, 1974). Other examples of physiological responses to noise include histological changes in the median lobe of the rat pituitary (Werner, 1959), hyperplasia of adrenals and a reduction in the lymphatic tissue of the thymus gland of the guinea-pig (Anthony & Harclerode, 1959), an alteration of the circulating eosinophil level in mice (Anthony, 1955) and even a reduction in total bodyweight of some primates (Sackler, Weltman, Bradshaw & Jurtshuk, 1959). The results of other studies indicate that auditory stimuli can induce regressive changes in various species resembling those produced by other stressful stimuli (Pfaff, 1974; Warfield, 1973; Zondek & Tamari, 1967). It is now known that there is considerable interspecific variation in sensitivity to different sound frequencies (~arfield, 1973). Fig. 1 indicates diagrammatically the reported frequency ranges to which the species shown are known to respond, together with an indication of those frequencies to which each species is most sensitive. From this it can be seen, for example, that mice are insensitive to sounds below 1 k Hz (the frequency of the Greenwich meantime 'pips' on the radio). In the case of rats, Crowley, Hepp-Reymond, Tabowitz & Palin (1965) have recorded cochlear microphonic potentials from both adults and infants to signals as low as 100 Hz; they also found, however, that the threshold increased rapidly below -1 kHz and that the rats' most sensitive frequency range is from 35-40 kHz.
Downloaded from lan.sagepub.com at Queen's University on March 6, 2015
G. CLOUGH
194
100 000
AND
J. A. L. FASHAM
C
ro·.·",·.: : : I::::::.
A
F
G .........
t········ •.....•• 1 :::::::: ........ ::::::::
H
20 000 10 000 5 000
Q):
",. ~.
e" 0: "
2 000
-•.. N
C1l
::I:
Qj: :
Q)' •
:: 0::;
.........; :
1 000 500
..... . -' .n. : :.
200 100
J
•.. Q)
EY? ........!
::~: .. C . .::0::: :.
: : .......... t"
"
•..
: :: : ..0: : : c:·
':0"
i:.~::! ....... ,-
50 : c: . C'
:::: ..~,:::~
20
.........
10 Fig. 1. Reported hearing range (stippled) and most sensitive frequency range (black) of some laboratory mammals, with sound frequency output of the 'silent' fire alarm. References: A Mikaelian & Ruben (1964), Mikaelian, Alford & Ruben (1965); B Finck & Goehl (1968), Finck & Sofouglu (1966); C Dice & Barto (1952), Ralls (1967); D Finck & Goehl (1968); Finck & Sofouglu (1966); E Crowley, Hepp-Reymond, Tabowitz & Palin (1965), Gourevitch & Hack (1966); F Wever (1959); G Wever (1959), Price (1963); H Robinson & Dadson (1956); J Fasham & Clough (1975).
Bearing these facts in mind it was decided to construct a device which produced a loud, low frequency noise suitable for use as an alarm signal for human beings whilst at the same time being below the frequency threshold (or at least outside the most sensitive frequency range) of those species commonly used as laboratory animals, in particular the rat and mouse.
Downloaded from lan.sagepub.com at Queen's University on March 6, 2015
A 'SILENT'
FIRE
MATERIALS
AND
ALARM
195
METHODS
The device developed produces pure tones alternating between 430 and 470 Hz, and operates from a continuous or pulsating d.c. supply of nominally )4V. To ensure operation at the end of long supply lines, it is designed to operate down to 5V. The alarm has an output of 3W with a 24W supply and the supply current is 250 mAo Details of the electronic circuitry and construction are available (Fasham & Clough, 1975). In order to assess the effect of the alarm on animals, 2 behavioural tests have been used: arousal from sleep; assessment of startle response-an abrupt reflexive movement of the entire body in response to a sudden, intense sound (Landis & Hunt, 1939)-and other visual indications of auditory disturbance. RESULTS
When the alarm is switched on in an animal room-giving a sound level of 97 dBC at 450 mm-rats and mice are not awakened from sleep and, if already awake, show no startle response, ear twitching or other indication of auditory disturbance. Rabbits and guinea-pigs show little more than 'mild disturbance' at this intensity and no visually appreciable response at all when the alarm is sounded in the corridor of the animal house-the site of an existing fire bell. As far as humans are concerned, however, the noise produced by the device is intensely irritating and disturbing and the Fire Officer and other persons interested in safety on the Carshalton site have agreed that the noise is very suitable as an alarm signal. The intensity of the sound produced was selected so that each existing fire bell could be replaced by one of the new alarms. DISCUSSION
The numerous effects of noise on animals are well documented, and range from audiogenic seizures, to teratogenic effects, trauma and irreversible deafness (for discussion see Pfaff, 1974; Warfield, 1973). The increasing use of audible warning devices, together with the need for their regular testing, creates a source of disturbance to animal facilities-that is, loud noises at irregular intervals, usually interspersed with relatively long periods of comparative quietness. Pfaff (1974) has outlined some of the problems of noise in the animal house, and the device described here was produced with the specific intent of reducing one source of stress to at least some species of laboratory animal. At Carshalton, it is intended to replace all fire bells in animal areas with the 'silent'
fire alarm. REFERENCES Anthony, A. (1955). Effects of noise on eosinophil levels of audiogenic seizure susceptible and seizure resistant mice. Journal of the Acoustical Society of America 27, 1150-1153.
Downloaded from lan.sagepub.com at Queen's University on March 6, 2015
196
G. CLOUGH
AND
J. A. L. FASHAM
Anthony, A. & Harclerode, J. E. (1959). Noise stress in laboratory rodents. II. Effects of chronic noise exposures on sexual performance and reproductive function of guinea pigs. Journal of the Acoustical Society of America 31, 1437-1440. Crowley, D. E., Hepp-Reymond, M. C., Tabowitz, D. & Palin, J. (1965). Cochlear potentials in the albino rat. Journal of Auditory Research 5, 307-316. Dice, L. R. & Barto, E. (1952). Ability of mice of the genus Peromyscus to hear ultrasonic sounds. Science, New York 116, 110-111. D'Souza, F. & Martin, R. D. (1974). Maternal behaviour and the effects of stress in tree -shrews. Nature, Lond9n 251, 309-311. Fasham, J. A. L. & Clough, G. (1975). A fire alarm for laboratories and animal rooms. Electronic Engineering 47, 27-28. Finck, A. & Goehl, H. (1968). Vocal spectra and cochlear sensitivity in the Mongolian gerbil. Journal of Auditory Research 8, 63-69. Finck, A. & Sofouglu, M. (\966). Auditory sensitivity of the Mongolian gerbil. Journal of Auditory Research 6, 313-319. Gourevitch, G. & Hack, M. H. (\966). Audibility in the rat. Journal of Comparative and Physiological Phychology 62, 289-291. Henry, K. H. (1967). Audiogenic seizure susceptibility induced in C57Blj6J mice by prior auditory exposure. Science, New York 158, 938-940. Iturrian, W. B. & Fink, G. B. (1968). Effect of noise in the animal house on seizure susceptibility and growth of mice. Laboratory Animal Care 18, 557-560. Landis, C. & Hunt, W. A. (1939). The startle pal/ern. New York: Farrar. Lane-Petter, W. (1963). Animals for research. London & New York: Academic Press. Mikaelian, D.O., Alford, B. R. & Ruben, R. J. (1965). Cochlear potentials and VITI nerve action potentials in normal and genetically deaf mice. Annals of Otology, Rhinology and Laryngology 74, 146-157. Mikaelian, D. O. & Ruben, R. J. (1964). Development of hearing in the CBAjJ mouse. Acta oto-laryngologica 59, 451-461. Pfaff, J. (1974). Noise as an environmental problem in the animal house. Laboratory Animals 8,347-354. Price, G. R. (1963). Middle ear muscle activity in the rabbit. L The loss threshold. Journal of Auditory Research 3, 221-231. Ralls, K. (1967). Auditory sensitivity in mice:- Peromyscus and Mus musclilas. Animal Behaviour 15, 123-128. Robinson, D. W. & Dadson, R. S. (1956). A redetermination of the equal loudness relations for pure tones. British Journal of Applied Physics 7, 166-181. Sackler, A. M., Weltman, A. S., Bradshaw, M. & Jurtshcuk, P. Jr (1959). Endocrine changes due to auditory stress. Acta endocrinologica, Copenhagen 31, 405-418. Warfield, D. (1973). The study of hearing in animals. In Methods of animal experimentation (ed. W. I. Gay), vol. 4, chap. 2. New York & London: Academic Press. Werner, R. (\959). Influence du son sur Ie lobe intermediaire de l'hypophyse de rat. Compte rendu de I' Association des anatomistes 104, 783-788. Wever, E. G. (1959). The cochlear potentials and their relationship to hearing. Annals of Otology, Rhinology and Laryngology 68, 975-989. Zondek, B. (1959). Studies on the mechanism of the female genital function. Fertility and Sterility 10, 1-14. Zondek, B. & Tamari, I. (1958). Stimulation of the anterior pituitary function with pronounced decrease in fertility by stimulation of the auditory organs. Preliminary note. Bulletin of the Research Council of Israel Section B, 7E, 155-156. Zondek, B. & Tamari, I. (1960). Effect of audiogenic stimulation on genital function and reproduction. American Journal of Obstetrics and Gynecology 80, 1041-1048. Zondek, B. & Tamari, T. (I 964a). Effect of auditory stimulation on reproduction. IV. Experiments on deaf rats. Proceedings of the Society for Experimental Biology and Medicine 116,636-637. Zondek, B. & Tamari, I. (l964b). Effect of audiogenic stimulation on genital function and reproduction. Ill. Infertility induced by auditory stimuli prior to mating. Acta endocrinologica, Copenhagen Suppl. 90, 227-234. Zondek, B. & Tamari, I. (1967). Effects of auditory stimuli on reproduction. In The effects of external stimuli on reproduction (ed. G. E. W. Wolstenholme & M. O'Connor). Ciba Foundation Study Group 26.
Downloaded from lan.sagepub.com at Queen's University on March 6, 2015
