Why do sounds have different pitches

Long prongs will bend more readily and therefore tend to vibrate at a lower frequency when struck. Volume , or loudness, is related to the strength, intensity, pressure, or power of the sound.

There are a few ways of varying the volume of a tuning fork. Touching the vibrating fork to a table after being struck produces a louder sound. When both the table and the tuning fork vibrate, more air molecules are moved than by the tuning fork on its own.

Touching a vibrating fork to clothes or your hand causes a damping effect on the vibrations reduction in size and the sound disappears. The energy from the vibrating fork is converted to moving your skin or clothes rather than moving air. Resonance is the tendency of an object to vibrate at maximum amplitude size at a certain frequency.

This frequency is known as the object's resonant frequency. Acoustic sound resonance is an important consideration for instrument builders, as most acoustic instruments use resonators think of the box of a guitar or a violin, or the hollow body of a drum. Describe the properties of sound. Per Class: tuning forks rubber mallet or the rubber bottom of a shoe resonance box optional. If using this as an activity, provide the materials above for each pair of students.

The vibrating object that creates the disturbance could be the vocal cords of a person, the vibrating string and sound board of a guitar or violin, the vibrating tines of a tuning fork, or the vibrating diaphragm of a radio speaker.

Regardless of what vibrating object is creating the sound wave, the particles of the medium through which the sound moves is vibrating in a back and forth motion at a given frequency.

The frequency of a wave refers to how often the particles of the medium vibrate when a wave passes through the medium. The frequency of a wave is measured as the number of complete back-and-forth vibrations of a particle of the medium per unit of time. If a particle of air undergoes longitudinal vibrations in 2 seconds, then the frequency of the wave would be vibrations per second. A commonly used unit for frequency is the Hertz abbreviated Hz , where. As a sound wave moves through a medium, each particle of the medium vibrates at the same frequency.

This is sensible since each particle vibrates due to the motion of its nearest neighbor. The first particle of the medium begins vibrating, at say Hz, and begins to set the second particle into vibrational motion at the same frequency of Hz. The second particle begins vibrating at Hz and thus sets the third particle of the medium into vibrational motion at Hz. The process continues throughout the medium; each particle vibrates at the same frequency. And of course the frequency at which each particle vibrates is the same as the frequency of the original source of the sound wave.

Subsequently, a guitar string vibrating at Hz will set the air particles in the room vibrating at the same frequency of Hz, which carries a sound signal to the ear of a listener, which is detected as a Hz sound wave.

The back-and-forth vibrational motion of the particles of the medium would not be the only observable phenomenon occurring at a given frequency. Since a sound wave is a pressure wave , a detector could be used to detect oscillations in pressure from a high pressure to a low pressure and back to a high pressure. The auditory cortex of the brain is located within a region called the temporal lobe and is specialized for processing and interpreting sounds see Figure 3.

The auditory cortex allows humans to process and understand speech, as well as other sounds in the environment. What would happen if signals from the auditory nerve never reached the auditory cortex?

Since many other areas of the brain are also active during the perception of sound, individuals with damage to the auditory cortex can often still react to sound. In these cases, even though the brain processes the sound, it is unable to make meaning from these signals. One important function of human ears, as well as the ears of other animals, is their ability to funnel sounds from the environment into the ear canal.

Though the outer ear funnels sound into the ear, this is most efficient only when sound comes from the side of the head rather than directly in front or behind it. When hearing a sound from an unknown source, humans typically turn their heads to point their ear toward where the sound might be located. People often do this without even realizing it, like when you are in a car and hear an ambulance, then move your head around to try to locate where the siren is coming from.

Some animals, like dogs, are more efficient at locating sound than humans are. Sometimes animals such as some dogs and many cats can even physically move their ears in the direction of the sound! Humans use two important cues to help determine where a sound is coming from. These cues are: 1 which ear the sound hits first known as interaural time differences , and 2 how loud the sound is when it reaches each ear known as interaural intensity differences.

If a dog were to bark on the right side of your body, you would have no problem turning and looking in that direction. This is because the sound waves produced by the barking hit your right ear before hitting your left ear, resulting in the sound being louder in your right ear. Why is it that the sound is louder in your right ear when the sound comes from the right? Because, like objects in your house that block or absorb the sound of someone calling you, your own head is a solid object that blocks sound waves traveling toward you.

When sound comes from the right side, your head will block some of the sound waves before they hit your left ear. This results in the sound being perceived as louder from the right, thereby signaling that that is where the sound came from. You can explore this through a fun activity. Close your eyes and ask a parent or friend to jingle a set of keys somewhere around your head. Do this several times, and each time, try to point to the location of keys, then open your eyes and see how accurate you were.

When an object vibrates quickly, high-pitched sounds are heard. Low-pitched sounds come from things that vibrate more slowly. Humans can hear sounds of different pitches, but there are sounds that they cannot hear.

Human ears cannot detect very low-pitched noises, known as infrasound, or very high-pitched noises, called ultrasound. The peaks of the waves on the graph are close together.