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In examining the potential impact of human-made sound on sea mammals, it was considered that whale hearing sensitivity might diminish with increasing ambient pressure. To test the effect of depth, two white whales made 885 dives to a platform at 5, 100, 200 or 300 m in the Pacific Ocean. Each stationing on the platform up to 12 minutes at a time, whales whistled when they heard a 500 ms tone from a hydrophone. With increasing depth, air density increase in the middle ear, sinuses, and nasal cavity changed each whale's whistle response, but did not attenuate hearing as it does in the aerial ear (of humans and other land mammals tested in pressure chambers) due to middle ear impedance changes. The findings support theories that sound is conducted through whale head tissues to the ear without the usual ear drum/ossicular chain amplification of the aerial middle ear. These first ever hearing tests in the open ocean demonstrate that whales hear as well at depth as near the surface; therefore, zones of influence for human made sounds are just as great throughout the depths to which whales dive, or at least to 300 m.

Despite the complexity and variability, the entity of sounds in particular time and space characterises the environment. Japanese people have an idea that the riverside environment provides important sound resources for comfort and relaxation, and attempt to include it in the local area planning. However, what is the riverain sound environment in bioacoustic senses? The Tone River, which covers a large area of mountains and plains in north and east of Tokyo, has historically been altered in many ways such as flood control and other human activities. In 1993-94, the sound environment survey was carried out from the lower reach of artificially constructed river banks, along the middle reach amidst the plain of agricultural activities to the upper reach of natural mountain forest tributaries. The present paper focuses upon the analysis methods to characterise the varieties of sound environment along the river. From identification of natural sound sources and examination of recorded samples using wave form, power spectrum and sonogram methods, I attempted to relate the sound source composition and their acoustic features to the land utilisation and structure of environment. It appears that the present method may provide a useful method to understand the structure of sound environment.

Within labyrinth fishes (Anabantoidei), croaking gouramis Trichopsis vittatus and pygmy gouramis T. pumila vocalize regularly during agonistic interactions. These vocalizations are broad-band pulsed sounds with high- pitched dominant frequencies (1-2.5 kHz), which contrast with the generally low-frequency hearing abilities of perciform fishes. Utilizing a recently developed auditory brainstem response recording technique, the auditory sensitivity was measured and compared to sound characteristics. The dominant frequencies of sounds were 1-2 kHz and 1.5-2.5 kHz for croaking and pygmy gouramis, respectively. Maximum low-frequency sensitivity for both species was 0.1-0.2 kHz. Maximum high-frequency sensitivity occurred between (3.8 and 2 kHz for croaking gouramis, which closely matched the best frequency of hearing. However, the best hearing frequency of pygmy gouramis was below 1.5 kHz, which indicated a mismatch between the two parameters. The correlation between sound production and perception in these fishes is likely to be facilitated by the suprabranchial airbreathing cavity, which lies close to the hearing and sonic organs and enhances both sound perception and emission at its resonant frequency. Additional examination of Macropodus opercularis, Trichogaster trichopterus and Colisa lalia revealed that all five gourami species could perceive sounds up to 5 kHz. The high-frequency hearing abilities of labyrinth fishes qualifies this group as hearing specialists.

Humpback whales produce cyclical sound sequences (called songs) that are composed of a variety of structured sound patterns. Past studies of sound patterns and individual sounds within songs have often assumed they are functionally homogeneous elements that are varied to convey information about the singer. Alternatively, differing sounds and sound patterns within songs may be functionally heterogeneous elements that vary for reasons unrelated to information content. To assess this possibility, humpback whale songs recorded in Hawaii from 1992-1995 were analyzed to determine whether whales consistently used some sound patterns more extensively than others and to measure the stability of the acoustic features of sound patterns. It was found that some patterns were consistently produced for long periods of time and that other patterns were consistently produced for short periods of time; acoustic features of both classes of sound patterns were highly stereotyped. The potential detectability of different sounds and sound patterns within songs was found to vary substantially. It is speculated that differences in detectability reflect differences in utility. Finally, in contrast to previous reports, comparisons of the sound patterns analyzed in this study with those described in past studies suggest that several sound patterns recur across years and populations.

Geographic variation is an important part of the process of speciation and variation in acoustic signals may play a role in reproductive isolation of populations and/or species. Although geographic variation in acoustic signals has been documented in many vertebrate species, it has not been well-documented in teleost fishes. Longear sunfish Lepomis megalotis (Centrarchidae) spawn on the substrate in clear, shallow, flowing water and the young are cared for by the father. Parental male longear sunfish use acoustic signals during the reproductive season, both for intra- and intersexual communication. Females may also use an acoustic signal during courtship. Sunfish calls were recorded using a hydrophone in streams around Austin, Texas. Calls were then digitized and analyzed with wavelet transforms. Playback experiments were conducted using an underwater speaker and digitized calls from multiple creeks. Fish appear to respond preferentially to signals from their own stream. These preliminary results are part of an ongoing investigation of the acoustic environment and its role in signal design of calls in longear sunfish.

Developmental and functional aspects of avian vocalizations will be treated. Field and laboratory studies on song development will be compared and the effects of live vs. tape tutoring on the sensitive phase, onset of subsong, time of song crystallization and quality of crystallized song will be discussed. Modes of cultural tradition will be reviewed including vertical, oblique and horizontal traditions, as well as traditions along sexual lines. Field and laboratory studies on the circannual cycles of neurogenesis in the HVC and RA song control centres in the brain will be compared and the results related to studies of vocal development. Evidence for stimulus filtering in vocal ontogeny will be reviewed and evidence for the effects of social interaction overriding ‘innate' preferences to learn conspecific song will be presented. These data will be interpreted in terms of Cody's ‘Character Convergence' hypothesis. The effects of vocalizations on gonadal recrudescence will be reviewed with emphasis on the synergistic vs. complementary roles of song vs. photoperiod discussed. Finally, evidence for the pituitary's circadian sensitivity to song vs. LD-cycle will be presented.