貓咪發(fā)出的“咕嚕咕嚕”的喉音可是有講究的,。一項(xiàng)新的研究表明，我們的貓科朋友在尋找食物時(shí)會(huì)改變它們的標(biāo)志音,，并加入了一種類似于嬰兒啼哭的高頻音質(zhì),，從而使得這種叫聲很難被忽略。
盡管豚鼠甚至大象都會(huì)發(fā)出咕嚕咕嚕的聲音,，但由貓發(fā)出的這種神秘的聲音無(wú)疑給人留下了最深刻的印象,。這種低低的呼嚕聲——大約為27赫茲，相當(dāng)于一架鋼琴發(fā)出的最低音符——聽起來就像是一種笑聲,，通常都意味著滿足,。有時(shí)當(dāng)一只貓患病或受傷時(shí)，這種聲音也會(huì)突然出現(xiàn),，多半是為了自我安慰,，尋求幫助，或者是加速自愈過程,。
英國(guó)布賴頓市蘇賽克斯大學(xué)的行為生態(tài)學(xué)家Karen McComb如今發(fā)現(xiàn)了這種聲音的另一個(gè)功能——為了吃到早餐,，她養(yǎng)的小貓Pepo每天清晨都會(huì)用堅(jiān)持不懈的喉音叫她起床。McComb在向其他幾位養(yǎng)貓的朋友“哭訴”錯(cuò)過的好夢(mèng)時(shí)獲悉,，他們也曾被寵物饑餓時(shí)發(fā)出的“咕嚕咕嚕”聲叫醒,。作為一名動(dòng)物交流專家，McComb開始研究是什么讓這些特別的呼嚕聲如此難以抗拒,。
她招募了10位貓主來記錄寵物覓食,，以及休息或玩耍時(shí)發(fā)出的喉音。接下來,，McComb和同事邀請(qǐng)50位具有不同養(yǎng)貓經(jīng)驗(yàn)的志愿者傾聽這些喉音的錄音,，并依據(jù)緊迫程度為它們分類。與同一只貓發(fā)出的并不迫切的喉音相比,，75%的志愿者——包括一些從未養(yǎng)過貓的人——始終認(rèn)為尋找食物的焦慮呼嚕聲聽起來更加急迫,，并且更讓人不舒服。
聲學(xué)分析揭示了其中的奧秘：這些迫切的呼嚕聲中隱藏了一種高頻的貓叫,，其頻率類似于人類嬰兒的啼哭聲,。呼嚕聲越大，聽者便會(huì)覺得越緊急,。當(dāng)McComb刪除了高頻的貓叫,，并將剩下的喉音完好無(wú)損地放給志愿者聽后，人們便都覺得呼嚕聲沒有之前那么緊急了。她和同事在7月14日出版的《當(dāng)代生物學(xué)》（Current Biology）雜志上報(bào)告了這一研究成果,。
從事貓如何發(fā)出喉音研究的美國(guó)路易斯安那州新奧爾良市Tulane大學(xué)的生物醫(yī)學(xué)工程師David Rice表示,，貓夸大它們的喉音可能還有其他的動(dòng)機(jī)。例如,，更高的頻率能夠幫助聲音更遠(yuǎn)的傳播,。
Rice說，無(wú)論如何,，這項(xiàng)研究支持了這樣一種觀點(diǎn),，即貓?jiān)谟?xùn)練它們的主人，而非相反的走勢(shì),。他說：“貓是一種相當(dāng)聰明的動(dòng)物,，它們很快便會(huì)知道什么有用以及什么沒用。”得克薩斯州A&M大學(xué)的獸醫(yī)Bonnie Beaver對(duì)此表示贊同,。她說：“這是一個(gè)反復(fù)試驗(yàn)認(rèn)知的經(jīng)典案例,。”（生物谷Bioon.com）
生物谷推薦原始出處：
Current Biology, 14 July 2009 doi:10.1016/j.cub.2009.05.033
The cry embedded within the purr
Karen McComb1,,Anna M. Taylor1,Christian Wilson1andBenjamin D. Charlton2
1 Centre for Mammal Vocal Communication Research, Department of Psychology, School of Life Sciences, University of Sussex, Brighton BN1 9QH, UK
2 Zoo Atlanta, Atlanta, Georgia, GA 30315-1440, USA
Summary
Despite widespread interest in inter-specific communication, few studies have examined the abilities of companion animals to communicate with humans in what has become their natural environment the human home [1,2]. Here we report how domestic cats make subtle use of one of their most characteristic vocalisations purring to solicit food from their human hosts, apparently exploiting sensory biases that humans have for providing care. When humans were played purrs recorded while cats were actively seeking food at equal amplitude to purrs recorded in non-solicitation contexts, even individuals with no experience of owning cats judged the solicitation purrs to be more urgent and less pleasant. Embedded within the naturally low-pitched purr, we found a high frequency voiced component, reminiscent of a cry or meow, that was crucial in determining urgency and pleasantness ratings. Moreover, when we re-synthesised solicitation purrs to remove only the voiced component, paired presentations revealed that these purrs were perceived as being significantly less urgent. We discuss how the structure of solicitation purrs may be exploiting an inherent mammalian sensitivity to acoustic cues relevant in the context of nurturing offspring.
