在人類社會(huì),，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(huì)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(dòng)物包括海洋哺乳動(dòng)物之中呢,？科學(xué)家已經(jīng)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(huì)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(xué)院水生生物研究所和三亞深?？茖W(xué)與工程研究所科研人員合作發(fā)表了一篇關(guān)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(hào)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(shù),，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(tuán)隊(duì)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(gè)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(hào)的頻率要比年輕中華白海豚發(fā)出的回聲定位聲信號(hào)頻率低大致16kHz,，以主動(dòng)補(bǔ)償其高頻聽覺能力的下降。該研究第一次證實(shí)在自然條件下鯨豚動(dòng)物的高頻聽覺能力也會(huì)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(guān)領(lǐng)域科學(xué)家及科普工作者的廣泛關(guān)注,。Science News在該論文發(fā)表后的第一時(shí)間以Could You Repeat That Click,？為題對(duì)該研究進(jìn)行了報(bào)道。INSIDE JEB也對(duì)該論文做了特別報(bào)道。
該項(xiàng)研究得到國家自然科學(xué)基金,、香港海洋公園保育基金等項(xiàng)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).
