Introduction Loudness of Sound
The sounds we encounter in our daily lives vary, and we are equipped with mechanisms to analyze and comprehend these variations. Mothers have a different voice from those of the children they speak to. Have you ever thought about why everyone has a different voice? We need to understand the loudness of sound, its pitch, and the difference between them.
What is the loudness of sound? Which factors determine it?
Answer:
There is a relationship between the loudness of a sound and its amplitude. In general, loudness refers to how large the amplitude of the sound wave is. The decibel (dB) scale for measuring loudness is directly proportional to the square of the amplitude of the vibration. Thus, noise is defined as sounds above 80 dB.
Explanation:
A person's perception of loudness is influenced by the amount of sound they hear. A sound's volume is determined by its intensity, which is itself governed by its frequency. Sounds are measured by their intensity or the energy they hold. Intensity is measured in decibels (dB). In this way, the loudness of sounds is determined by its intensity. There are two factors that determine how intense a sound is: the size of the sound waves and the distance from their source.
Sound waves are measured according to their amplitude.
Wave amplitude is determined by the energy that caused them.
Waves with larger amplitudes have more energy and are more intense, so they are louder.
The following table gives us data about different sound sources.
In sound waves, the amplitude is directly associated with loudness, since all waves have the same amplitude. An ocean wave on a calm day may only be a foot high, whereas a surf wave can reach heights of 10 feet or more. As the amplitude increases during a storm, it may reach 40 to 50 feet.
Pitch of sound
Depending on how fast the waves vibrate, the effect is different.
Sound that has a high pitch and a high frequency is called shrill or shrill sound. A sound's pitch is expressed as its frequency of vibration if it has a lower pitch.
While birds produce high-pitched sounds, lions produce low-pitched sounds when roaring.
An average woman's voice has a higher pitch than an average man's.
Pitch vs Loudness
Although these two phenomena sometimes appear to be the same, they are not exactly the same. The key difference is the quality of the tone. Sound pitch is a response our ears have to a sound's frequency. In contrast, loudness is determined by the strength of the wave. Generally speaking, pitch accounts for the difference in voice quality between individuals.
The Pitch and loudness of sounds are determined by their frequency and amplitude, respectively. It is amazing that trained musicians have the ability to detect a difference in frequency between sounds that is as little as 2 Hz.
The Loudness of Sound Formula
L = log (I)
Where I: Intensity of sound.
Difference of loudness, L2 - L1 = 10 log10 \[(\frac {I_1}{I_0})\]
The Intensity of the Sound
Accordingly, the intensity is defined as the ratio of energy per unit time per unit area, and since the ratio of energy to time is the same as the power per unit area, the intensity is simply the power per unit area.
Intensity = \[\frac{\text{Energy}}{\text{(Time * Area)}}\] or Intensity = \[\frac{\text{Power}}{\text{Area}}\]
The units used to express the intensity of a wave of sound are Watts per meter2.
FAQs on Loudness of Sound
1. What is meant by the loudness of a sound?
Loudness is our perception of how strong or intense a sound is. It describes whether a sound is soft or loud to a listener. The primary factor that determines loudness is the amplitude of the sound wave; a larger amplitude results in a louder sound.
2. How is loudness different from the intensity of a sound?
While related, they are not the same. Intensity is a physical, measurable quantity of sound energy passing through a specific area. Loudness is the subjective way our ears and brain perceive that energy. A sound with high intensity will be perceived as loud, but loudness can vary slightly from person to person.
3. What is the relationship between the loudness of a sound and its amplitude?
The relationship is direct and simple: the greater the amplitude of a sound wave, the louder the sound is perceived to be. For example, when you strike a drum gently, it creates a sound wave with a small amplitude, resulting in a soft sound. If you strike it with more force, you create a wave with a larger amplitude, which we hear as a much louder sound.
4. What is the difference between loudness and pitch?
Loudness and pitch are two distinct characteristics of sound that are often confused. Here’s a simple breakdown:
- Loudness is determined by the amplitude of a sound wave and describes if a sound is loud or soft.
- Pitch is determined by the frequency of a sound wave and describes if a sound is high (like a whistle) or low (like a bass drum).
5. Can you provide some examples of loudness from everyday life using the decibel (dB) scale?
Certainly. The decibel scale helps us understand the loudness of different sounds:
- A quiet whisper: Around 30 dB
- Normal conversation: Around 60 dB
- A vacuum cleaner: Around 75 dB
- City traffic: Around 85 dB
- A rock concert or jet engine: Can exceed 110-120 dB
6. Why does a sound seem softer when you move farther away from it?
This happens because as sound waves travel outward from a source, their energy spreads out over a larger and larger area. This spreading out causes the sound's intensity to decrease with distance. Since our ears perceive loudness based on the intensity of the sound that reaches them, the sound naturally seems softer the farther away we are.
7. If two different sounds have the same decibel level, will they always sound equally loud?
Not necessarily. The human ear is not equally sensitive to all frequencies. We are most sensitive to frequencies in the mid-range, like those of human speech. Therefore, a mid-frequency sound at 70 dB might be perceived as louder than a very low-frequency or very high-frequency sound at the exact same 70 dB level. This highlights how loudness is a subjective perception.
