Songbirds use pulse tone register in two voices to generate low-frequency sound.

Penguins use the two-voice system to recognize each other.

The sound-producing structure in birds is the syrinx, which is usually a two-part organ located at the junction of the bronchi. As each branch of the syrinx produces sound independently, many birds have two acoustic sources. Thirty years ago, we had anatomical, physiological and acoustical evidence of this two-voice phenomenon but no function was known. In songbirds, often these two voices with...

Channels for Vocal Communication in a Small Passerine Bird

Songbirds such as the eastern towhee, Pipilo erythrophthalmus, are able to produce and hear a wide range of sound frequencies (~1.5-8 kHz) but tend to generate midrange sound frequencies between ~3 and 4 kHz in their vocalizations. This tendency might be explained if pressures for producing broadband sounds (~1.5-8 kHz) are opposed by pressures for producing midrange sound frequencies (~3.5 kHz...

Critique of Research Books (Art) / Voices to See: A Review of Sound and Music in Documentaries, Mohammad Nasr Ahadi

Effect of Exposure to a Mixture of Organic Solvents on Hearing Thresholds in Petrochemical Industry Workers

Introduction: Hearing loss is one of the most common occupational diseases. In most workplaces, workers are exposed to noise and solvents simultaneously, so the potential risk of hearing loss due to solvents may be attributed to noise.  In this study we aimed to assess the effect of exposure to mixed aromatic solvents on hearing in the absence of exposure to hazardous noise.   Materials and Met...

Acoustic Sensitivity of the Saccule and Daf Music

  Introduction:   The daf is a large Persian frame drum used as a musical instrument in both popular and classical music which can induce a percussive sound at low frequencies (146–290 Hz) with peaks of up to 130 dBspl. The percussive sounds have a power distribution in the region of saccular sensitivity. In view of the saccular stimulation by sound in humans, we decided to use cervical vestibu...