Abstract Sciaenids are a kind of economic oceanic fish with the most dynamic vocal activity. It is important to find out what type of sound a soniferous fish can make. Therefore, I used this acoustic character as a tool to study the distribution of sciaenids in order to manage their fisheries. In the previous researches, scientist found that there were eight types of sounds (A~H type) appearing on the coastal areas of Yunlin, and the frequency range of the H-type sound could reach to 8000Hz. This sound was suspected to be made by Otolithes ruber. Connaughton (1994) and Sprague (2000) mentioned that the differences of length, weight, and tension of the sonic muscle and the amount of protein and glycogen affect the types of sounds emitted. To reveal the producer of high-frequency sound, this research analyzed and compared the length, width, thickness and somatic of sonic muscle and the amount of protein and glycogen in seven sciaenid species occuring on the west coast of Taiwan (Johnius tingi, Johnius sina, Johnius amblycephalus, Johnius amblycephalus, Pennahia argentata, Chrysochir aureus, and Otolithes ruber), then to find if the differences of physic parameter and energy supplication are the major factors making O. ruber produce high frequency of sound. In this research, I found that the length of O. ruber¡¦s sonic muscle was shorter than that other of sciaenids. However the weight of sonic muscle did not significantly differ although it was still the lightest one (2.33¡Ó1.00g). The amount of protein (20.37¡Ó0.67¢M) and glycogen (0.33¡Ó0.11¢M) in O. ruber was higher than that of other species and the cross section of sonic muscle fiber was smaller. These characteristics are suitable for O. ruber to make a high-frequency sound. Because of the sound is believed to be made by rubber, so passive sonar was applied to investigate the distribution of this sound type on the estuaries along the west coast of Taiwan (Tam-Shui River, Tou-Chien River, Ta-Chia River, Cho-sui River, Zeng-Wen River, and Kao-Ping River) to represent distribution of O. ruber and its seasonal change of vocal activity. Acoustic activity reached it peak in spring then decreased through summer, autumn, and winter. More sounds were found in the estuaries south of the Cho-sui River (including Cho-sui, Zeng-Wen, and Kao-Ping River) than those north of this river (including Ta-Chia, Tou-Chien, and Tam-Shui River).