Refraction of Sound Waves

Updating you all once again, here is a post on the refraction of sound waves and how it relates to a dolphin's 'sight'! Also, a good news is that my professor, Dr.Tan has actually read my blog and found it interesting! I am so happy :D

Refraction occurs when sound waves travel through and medium and back.

http://m.eet.com/media/1064485/sound5_fig1.15.jpg
Sound wave through different media

This is due to the differences in the speed of sound. Sound waves bend when parts of the wave front travel at dissimilar speeds.

http://www.patana.ac.th/secondary/science/anrophysics/ntopic4/images/wavefront.gif
Picture of a Wave Front

By being able to sense ultrasonic(sound waves with frequencies above 20000 hertz) waves, dolphins can 'see' through the bodies of other animals and people.

Have you learnt new things?

Until next time!

Dolphin Language

     Even though I am having a flu, I feel so excited to share this piece of information with all of you, that I must do it now! So prepare yourselves for this interesting dolphin information!

There are variations in the sounds that dolphins make in air and underwater. Sound waves travel by passing vibrations from molecule to molecule. They travel slowest in air, 4.5 times faster in water, and the fastest in solids. In air, the molecules are spaced far apart and thus it is harder for the molecules to collide together passing on vibrations. Whereas, in liquid and solids, where molecules are spaced closer together, facilitating collisions and thus allowing sound waves to travel faster.

Factors affecting Speed of Sound in Air:

• Wind Conditions
• Temperature: Sound travel faster in higher temperatures.
• Humidity: Water vapour in the air increases speed of sound. 

     In air, dolphins produce sounds by letting out air through their blowholes. They can change the sounds by controlling the size and shape of the blowhole opening. They do this to attract people to their lagoons.

This is a video of my wife making a dophin sound with a balloon. 

Try it! It's fun!

   Underwater, dolphins produce 3 types of sounds.

1.     Whistles: Used for self-identification.

To hear the sound:

http://www.dolphins.org/images/PandoraWhistles1.wav

Different species of dolphins have different frequency range of whistles. This helps them to identify themselves as a school of dolphins. For example, bottlenose dolphins have a range of 2 to 24 KHz.

2.     Clicks/Echolocation: Used for navigation

To hear the sound:

http://www.dolphins.org/images/CalusaClicks1.wav

3. Burst Pulses: Used to express emotions

Here is an interesting video on dolphins playing with air rings.

http://www.youtube.com/watch?v=6DDcUDsZBVY

How Dolphins Perceive their Surroundings!

I met the renowned Dr. Whales today. He looks so stunning in person. It was my honor. He is the one who inspired me to do this blog post today. So here goes!

I will be telling you about how dolphins perceive their surrounding.

      Firstly, dolphins use echolocation as a method of sight in the ocean. By emitting sound waves, dolphin perceive their surroundings by interpreting the resulting echo. The dolphin emits low frequency sound waves for an overall of their surroundings and high frequency waves for examining things in detail. By increasing the frequency of the sound waves, velocity increases and the rate of returning echoes increases correspondingly. Each object has its unique, natural frequency, which changes in accordance with its elasticity and shape. Hence, the returning echoes allow the dolphin to recognize surrounding objects. As such, the dolphin can in a way “see” its surroundings “more clearly” as it is able to receives more information to detect its surroundings.

Echolocation
http://www.dolphins-world.com/images/echolocation.jpg

     Secondly, as the dolphin moves about, it continually emits increasing frequency of the sound waves such that the returning echoes will collide with them. The dolphin then hears the ‘’beat frequency’’, which is generated by the two colliding signals, to determine its distance between an object and itself. In constant motion, the beat frequency remains constant. In nearing distances, the beat frequency becomes lower. Thus, the pitch that the dolphin picks up is lower and it would know if the object is near to it or not.

Receiving sound waves
http://www.seaworld.org/infobooks/Bottlenose/images/echolocation.gif

Isn't this interesting? The mind of a dolphin is so complex, mystical and exciting! I cannot wait to share more of my research content with everyone! Check my blog constantly for more updates! :D

Reflection of Sound Waves

Hello everyone! Today, I will be talking about the reflection of sound waves, also known as ECHO! Isn't that exciting? This post is a must read if you want to have a clearer idea of echolocation.

After carrying out various experiments at my lab, I also found out that the amount of energy carried by the reflected sound wave varies with the type of surface. The amount of energy is large if the surface is firm and smooth, and less if the surface is soft and rough. Also, for sound reflected off smooth surface, the angle of incidence equals to angle of reflection.

http://www.physicsclassroom.com/Class/refln/u13l1d3.gif
A picture to illustrate the concept of sound waves on different objects

I got to go now! Dinner time with my lovely wife.

Sound Waves: Reply to My Reader

So I received my first comment from my No. 1 fan! :D 

He asked me what sound waves are, so this is my reply:

There are two kinds of waves, transverse and longitudinal. 

Here is a picture of both of them:

http://w3.shorecrest.org/~Lisa_Peck/Physics/All_Projects/Biggie_Project/2010/meghan/meghan1/longitudal%20compresion%20waves.jpg

Sound waves are longitudinal waves. A longitudinal wave is in which the particles of the medium travel in the direction of the propagation of the wave. In a sound wave, there can be two types of regions, either compression or rarefaction. The compressions are regions of high air pressure while the rarefactions are regions of low pressure.

The following picture will help to illustrate the concept of compression and rarefaction:

http://images.tutorvista.com/cms/images/95/longitudinal-waves-rarefaction.jpeg

Enjoy this video I made with my friends!

Feel free to ask me more questions on Dolphins! I will try my very best to answer your questions.

Let's go, Dolphin Lovers! <3

My Amazing Trip to Dolphin Wonderland

Today, I went for an adventure at Dolphin Wonderland and had some amazing discoveries. Dolphins are really magical creatures! Do you know that they have bad eyesight? So how do they know what is around them? Let me tell you.

The smart me found out that dolphins have a nasal sac which they use to send out rapid clicks that passes through their melon, also known as their forehead. Interesting right? Indeed! The dolphin’s nasal sacs vibrates, causing it’s melon to also vibrate, and thereafter influencing surrounding water molecules to vibrate. As the water molecules vibrate, kinetic energy is transferred to neighbouring water molecules. This continuous process provides an extensive medium for the sound waves emitted from the dolphin to reach surrounding objects. The vibration of water molecules causes the rapid clicks (sound waves) to travel through the water in the form of a compression wave. The sound waves bounce off the surrounding objects and are reflected back to the dolphin, allowing it to perceive the size and distance of an object from it. Cool right?

My wife is calling me now. I have to go. Stay tuned!

Nasal sac refers to the air sacs below the blowhole.
http://www.emeraldinsight.com/content_images/fig/0870330101004.png

P.S.The water does not move from the dolphin to the object. The water molecules are only temporarily displaced from their rest position. After which those particles in the medium will return to their fixed positions. It is the sound waves that transfer energy through the medium, from the dolphin to the object.

Enjoy this picture of a derp dolphin.
http://s3-ec.buzzfed.com/static/enhanced/webdr03/2013/2/22/12/anigif_enhanced-buzz-21852-1361553389-10.gif