在人類社會，老年性耳聾是一種較為常見的現(xiàn)象,，多數(shù)人的聽覺能力尤其是高頻聽覺能力都會隨著年齡的增長而下降。那么,，這一現(xiàn)象是人類所特有還是普遍存在于其它哺乳動物包括海洋哺乳動物之中呢,？科學家已經注意到人工飼養(yǎng)條件下的寬吻海豚和偽虎鯨的聽覺能力尤其是高頻聽覺能力會隨著年齡的增長而下降，但并不清楚這是一種自然現(xiàn)象還是由人工飼養(yǎng)環(huán)境引起,。近期,，中國科學院水生生物研究所和三亞深海科學與工程研究所科研人員合作發(fā)表了一篇關于一頭擱淺的年齡超過40歲的年老中華白海豚的聽覺能力和回聲定位聲信號特征的研究論文,。
通過采用非損傷性聽覺誘發(fā)電位（non-invasive auditory evoked potential）的技術,，科研人員發(fā)現(xiàn),，該年老中華白海豚的高頻聽覺能力要明顯低于該研究團隊之前研究過的一頭較年輕的（大約13歲）中華白海豚的聽覺能力[Li SH， Wang D,， Wang KX,， etc. 2012. Evoked-potential audiogram of an Indo-Pacific humpback dolphin (Sousa chinensis). The Journal of Experimental Biology， 215(17)： 3055–3063],。年老中華白海豚的高頻聽力范圍比年輕個體低30-40kHz,。另外，科研人員還發(fā)現(xiàn),，該年老中華白海豚發(fā)出的回聲定位聲信號的頻率要比年輕中華白海豚發(fā)出的回聲定位聲信號頻率低大致16kHz,，以主動補償其高頻聽覺能力的下降。該研究第一次證實在自然條件下鯨豚動物的高頻聽覺能力也會隨著年齡的增長而下降,，因此老年性耳聾現(xiàn)象并非人類所特有,。
該論文發(fā)表后，引起了相關領域科學家及科普工作者的廣泛關注,。Science News在該論文發(fā)表后的第一時間以Could You Repeat That Click,？為題對該研究進行了報道。INSIDE JEB也對該論文做了特別報道,。
該項研究得到國家自然科學基金,、香港海洋公園保育基金等項目的資助。（生物谷Bioon.com）
生物谷推薦的英文摘要
The Journal of Experimental Biology doi: 10.1242/?jeb.091504
Possible age-related hearing loss (presbycusis) and corresponding change in echolocation parameters in a stranded Indo-Pacific humpback dolphin
Songhai Li1,，2,，*， Ding Wang2,， Kexiong Wang2,， Matthias Hoffmann-Kuhnt1， Nimal Fernando3,， Elizabeth A. Taylor1,， Wenzhi Lin4， Jialin Chen4 and Timothy Ng5
The hearing and echolocation clicks of a stranded Indo-Pacific humpback dolphin (Sousa chinensis) in Zhuhai,， China,， were studied. This animal had been repeatedly observed in the wild before it was stranded and its age was estimated to be ~40 years. The animal's hearing was measured using a non-invasive auditory evoked potential (AEP) method. Echolocation clicks produced by the dolphin were recorded when the animal was freely swimming in a 7.5 m (width)×22 m (length)×4.8 m (structural depth) pool with a water depth of ~2.5 m. The hearing and echolocation clicks of the studied dolphin were compared with those of a conspecific younger individual， ~13 years of age. The results suggested that the cut-off frequency of the high-frequency hearing of the studied dolphin was ~30–40 kHz lower than that of the younger individual. The peak and centre frequencies of the clicks produced by the older dolphin were ~16 kHz lower than those of the clicks produced by the younger animal. Considering that the older dolphin was ~40 years old,， its lower high-frequency hearing range with lower click peak and centre frequencies could probably be explained by age-related hearing loss (presbycusis).
