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Sound travels about four times faster in seawater than in air: roughly 1,500 metres per second, against about 340 in air.

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Sound is a wave of pressure passed from molecule to molecule. It travels faster through materials that resist being squeezed, and water is far harder to compress than air. Water is also much heavier than air, which on its own would slow sound down, but its stiffness wins by a wide margin. In the sea the speed also changes with temperature, pressure and saltiness. In many oceans, around 1,000 metres down, these effects create a layer called the SOFAR channel, which bends sound back towards its centre and lets low sounds travel thousands of kilometres. Navies have used it to track submarines and detect distant explosions, and some whales' low calls may carry hundreds of kilometres through it.

Türkçe oku
Ses deniz suyunda havadakinden yaklaşık dört kat hızlı yayılır: saniyede 1.500 metre kadar, havada ise yaklaşık 340 metre.

Ses, molekülden moleküle aktarılan bir basınç dalgasıdır. Sıkıştırılmaya direnen maddelerde daha hızlı ilerler; su da havaya göre çok daha zor sıkışır. Suyun havadan çok daha ağır olması tek başına sesi yavaşlatırdı, ama sıkışmaya karşı direnci bu etkiyi fazlasıyla bastırır. Denizde sesin hızı sıcaklığa, basınca ve tuzluluğa göre de değişir. Birçok okyanusta 1.000 metre dolayında bu etkiler SOFAR kanalı denen bir katman oluşturur: Ses bu katmanın ortasına doğru bükülür ve alçak sesler binlerce kilometre uzağa taşınabilir. Donanmalar bu kanalı denizaltıları izlemek ve uzaktaki patlamaları duymak için kullandı; bazı balinaların pes sesleri de bu yolla yüzlerce kilometre öteye ulaşabiliyor.

Sources and further reading

Background reading: Underwater acoustics
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