Distinguish between loudness and intensity of sound

Be able to describe what physical characteristic of sound predicts perceived loudness. Know the unit of loudness (decibel) and sound pressure level. Be able to explain the relationship between perception loudness and stimulus intensity. The most direct physical correlate of loudness is sound intensity (or sound pressure) measured close to the eardrum. However, many other factors also influence the loudness of a sound, including its frequency content, its duration, and the context in which it is presented. Some of the earliest psychophysical studies of auditory perception, going back more than a century, were aimed at examining the relationships between perceived loudness, the physical sound intensity, and the just-noticeable differences in loudness (Fechner, 1860; Stevens, 1957). The loudness of a given sound is closely associated with the amplitude of the sound wave. Higher amplitudes are associated with louder sounds. Loudness is measured in terms of decibels (dB), a logarithmic unit of sound intensity. A typical conversation would correlate with 60 dB; a rock concert might check in at 120 dB. A whisper 5 feet away or rustling leaves are at the low end of our hearing range; sounds like a window air conditioner, a normal conversation, and even heavy traffic or a vacuum cleaner are within a tolerable range. However, there is the potential for hearing damage from about 80 dB to 130 dB: These are sounds of a food processor, power lawnmower, heavy truck (25 feet away), subway...

Solution Intensity of a sound wave is defined as the amount of sound energy passing through a unit area per second. Loudness is a measure of the response of the ear to the sound. The loudness of a sound is defined by its amplitude. The amplitude of a sound decides its intensity, which in turn is perceived by the ear as loudness.

Table of Contents • • • • • • • How can we distinguish between two sounds having same loudness and pitch? To distinguish sounds having same pitch and loudness, timbre or quality can be used to distinguish between the sounds. The property of sound by virtue of which we can distinguish between sounds having same loudness and pitch is called quality. What is the difference between high amplitude and low amplitude sound waves? What is the difference between sounds with high and low amplitude? High amplitude sound waves are taller than low amplitude. This gives them more energy and a louder sound. S waves are more powerful and damaging than P waves. Loudness Intensity Loudness is the measure of the response of the ear to the sound. Intensity is the sound power per unit area. How do we distinguish between two sounds? Solution: Pitch distinguishes two sounds of the same loudness and timbre. The sensation of a frequency is commonly referred to as pitch. Frequency is directly proportional to pitch, higher the frequency, higher the pitch which means shrill sound and lower the frequency, lower the pitch which means flat sound. How can we differentiate between two sounds? Why are sounds different? As you know, there are many different sounds. Fire alarms are loud, whispers are soft, sopranos sing high, tubas play low, every one of your friends has a different voice. The differences between sounds are caused by intensity, pitch, and tone. What is the difference between low and high fre...

Loudness is typically measured in decibels, #"dB"#. In these units, the relationship is #L_I = 10log(I/I_0)# where #L_I# is the #I# is the sound's intensity, and #I_0# is the intensity of the reference (usually in air). #I_0 = "1 pW/m"^2# (picowatts per meters squared) This essentially tells you that we perceive something as being loud in a relative manner. • If there is a lot of background noise, a song on the car radio will seem quiet, even if the volume is normal. • In a completely quiet room, someone dropping a pin is noticeably loud, even though it may not be loud on an absolute level. By the way, notice how this resembles the Beer-Lambert Law of absorption: #A = -log(I/I_0)# So, one can think of loudness then as analogous; the darker the substance, the greater its absorbance. However, there comes a point where it's so dark that the absorbance hardly changes. The mathematical trend it follows is similar with sound intensity levels in that the relative difference in loudness at higher loudness is smaller than at lower loudness.

The amount of sound energy passing eachsecond through the unit area is called theintensity of sound. We sometimes use theterms “loudness” and “intensity”interchangeably, but they are not the same.Loudness is a measure of the response of theear to the sound. Even when two sounds areof equal intensity, we may hear one as louderthan the other simply because our ears detect it better. So, loudness is the subjective quantity but intensity is the objective quantity.