Journal of Comparative Physiology A

, Volume 162, Issue 6, pp 799–813 | Cite as

The acoustic role of tracheal chambers and nasal cavities in the production of sonar pulses by the horseshoe bat,Rhinolophus hildebrandti

  • Roderick A. Suthers
  • David J. Hartley
  • Jeffrey J. Wenstrup


The acoustic role of the enlarged, bony, nasal cavities and rigid tracheal chambers in the horseshoe bat,Rhinolophus hildebrandti (Fig. 2) was investigated by determining the effect of their selective filling on the nasally emitted sonar pulse and on the sound traveling backwards down the trachea.

Normal sonar signals of this bat contain a long constant frequency component with most energy in the second harmonic at about 48 kHz. The fundamental is typically suppressed 20 to 30 dB below the level of the second harmonic (Fig. 1).

None of the experimental manipulations described affected the frequency of the sonar signal fundamental.

Filling the dorsal and both lateral tracheal chambers had little effect on the emitted vocalization, but caused the level of the fundamental component in the trachea to increase 15 to 19 dB in most bats (Table 2). When only the dorsal chamber or only the two lateral chambers were filled, the effect was less striking and more variable (Tables 3 and 4), suggesting that the tracheal fundamental is normally suppressed by acoustic interaction between these three cavities.

Filling the enlarged dorsal nasal cavities had no effect on the tracheal sound. The effect of this treatment on the nasally emitted sonar pulse was inconsistent. Sometimes the fundamental increased 10 to 12 dB, other times the intensity of all harmonics decreased; in still other cases the second, third or fourth harmonic increased, but the fundamental remained unchanged (Tables 5, 6, and 7).

When bats were forced to vocalize through the mouth, by sealing the nostrils, there was a prominent increase in the level of the emitted fundamental (10 to 21 dB) and in the fourth harmonic (6 to 17 dB). In one instance there was also a significant increase in the level of the third harmonic (Tables 8 and 9). The supraglottal tract thus filters the fundamental from the nasally emitted sonar signal, although the role of the inflated nasal cavities in this process is unclear.

We conclude that a high glottal impedance acoustically isolates the subglottal from the supraglottal vocal tract. The tracheal chambers do not affect the emitted sonar signal, but may attenuate the fundamental in the trachea and prevent it from being reflected from the lungs back towards the cochlea. It may be important to prevent the reflected fundamental from stimulating the cochlea, via tissue conduction, along multiple indirect pathways which would temporally smear cochlear stimulation.

Tracheal and nasal chambers, by suppressing the internally reflected and externally radiated components, respectively, of the laryngeal fundamental, may enable horseshoe bats to rely on the tissue-conducted fundamental as a reference or marker of its own laryngeally generated sound which could be useful in processing sonar information.


Sonar Nasal Cavity Vocal Tract Tissue Conduction Sonar Signal 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Berg Jw van den (1960) An electrical analogue of the trachea, lungs and tissues. Acta Physiol Pharmacol Neerland 9:361–385Google Scholar
  2. Elias H (1907) Zur Anatomie des Kehlkopfes der Microchiropteren. Morphol Jahrb 37:70–118Google Scholar
  3. Fant G (1970) Acoustic theory of speech production. Mouton, Paris, pp 328Google Scholar
  4. Fattu JM, Suthers RA (1981) Subglottic pressure and the control of phonation by the echolocating bat,Eptesicus fuscus. J Comp Physiol 143:465–475Google Scholar
  5. Hayes WL (1981) Statistics. 3rd edn. Holt, Rinehart and Winston, New YorkGoogle Scholar
  6. Kick SA, Simmons JA (1984) Automatic gain control in the bat's sonar receiver and the neuroethology of echolocation. J Neurosci 4:2725–2737Google Scholar
  7. Kinsler LE, Frey AR (1962) Fundamentals of acoustics. 2nd edn. Wiley, New YorkGoogle Scholar
  8. Kobler JB, Wilson BS, Henson OW Jr, Bishop AL (1985) Echo intensity compensation by echolocating bats. Hearing Res 20:99–108Google Scholar
  9. Long GR, Schnitzler H-U (1975) Behavioural audiograms from the bat,Rhinolophus ferrumequinum. J Comp Physiol 100:211–219Google Scholar
  10. Matsumura S (1979) Mother-infant communication in a horseshoe bat (Rhinolophus ferrumequinum nippon): development of vocalization. J Mammal 60:76–84Google Scholar
  11. Möhres FP (1953) Über die Ultraschallorientierung der Hufeisennasen (Chiroptera: Rhinolophinae). Z Vergi Physiol 34:547–588Google Scholar
  12. O'Neill WE, Schuller G, Radtke-Schuller S (1985) Functional and anatomical similarities in the auditory cortices of the Old World horseshoe bat and neotropical mustached bat for processing of similar biosonar signals. Assoc Res Otolaryngol, Abstr 8th Midwinter Res Meeting, p 148Google Scholar
  13. Pye JD (1967) Synthesizing the waveforms of bats' pulses. In: Busnel R-G (ed) Animal sonar systems, biology and bionics. Lab Physiol Acoust, INRA-CNRZ, Jouy-en-Josas, vol I, pp 43–64Google Scholar
  14. Pye JD (1968) Animal sonar in air. Ultrasonics 6:32–38Google Scholar
  15. Pye JD (1979) Echolocation signals and echoes in air. In: Busnel R-G, Fish JF (eds) Animal sonar systems. Plenum, New York, pp 309–353Google Scholar
  16. Pye JD, Flinn M, Pye A (1962) Correlated orientation sounds and ear movements of horseshoe bats. Nature 196:1186–1188Google Scholar
  17. Roberts LH (1972) Variable resonance in constant frequency bats. J Zool (Lond) 166:377–348Google Scholar
  18. Roberts LH (1973) Cavity resonances in the production of orientation cries. Period Biol 75:27–32Google Scholar
  19. Roverud RC, Grinnell AD (1985) Echolocation sound features processed to provide distance information in the CF/FM bat,Noctilio albiventris: evidence for a gated time window utilizing both CF and FM components. J Comp Physiol A 156:457–469Google Scholar
  20. Suga N, O'Neill WE, Kujirai K, Manabe T (1983) Specificity of combination-sensitive neurons for processing of complex biosonar signals in auditory cortex of the mustached bat. J Neurophysiol 49:1573–1626Google Scholar
  21. Suga N, Schlegel P (1972) Neural attenuation of responses to emitted sounds in echolocating bats. Science 177:82–84Google Scholar

Copyright information

© Springer-Verlag 1988

Authors and Affiliations

  • Roderick A. Suthers
    • 1
  • David J. Hartley
    • 1
  • Jeffrey J. Wenstrup
    • 1
  1. 1.School of Medicine and Department of BiologyIndiana UniversityBloomingtonUSA

Personalised recommendations