Concept explainers
Ever since seeing Figure 16.22 in the previous chapter, you have been fascinated with the hearing response in humans. You have set up an apparatus that allows you to determine your own threshold of hearing as a function of frequency. After performing the experiment and recording the results, you graph the results, which look like Figure P17.22. You are intrigued by the two dips in the curve at the right-hand side of the graph. You measure carefully and find that the minimum values of these dips occur at 3 800 Hz and 11 500 Hz. Performing some online research, you discover that the outer canal of the human ear can be modeled as an air column open at the outer end and closed at the inner end by the eardrum. You use this information to determine the length of the outer canal in your car.
Figure P17.22
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Physics for Scientists and Engineers
- A sound wave with intensity 2 x 10 -3 W/m2 is perceived to be modestly loud. Your eardrum is 6 mm in diameter. How much energy will be transferred to your eardrum while listening to this sound for 1 minute?arrow_forwardSound is detected when a sound wave causes the eardrum to vibrate. Typically, the diameter of the eardrum is about 8.4 mm in humans. When someone speaks to you in a normal tone of voice, the sound intensity at your ear is approximately 1.0 × 10-6 W/m². What is the power delivered to your eardrum? Express your answer in watts. P = 17 ΑΣΦ ? Warrow_forwardSound is detected when a sound wave causes the tympanic membrane (the ear drum) to vibrate. Typically, the diameter of this membrane is about 8.4 mm in humans. A) how much energy is delivered to the eardrum each second when someone whispers (20 dB) into your ear? B) to comprehend how sensitive the ear is to very small amounts of energy, calculate how fast a typical 2.0 mg mosquito would have to fly (in mm/s) to have this amount of kinetic energy.arrow_forward
- Sound waves travel at roughly 340 m/s at room temperature. The minimum hearing range of a human is 20Hz. a) What is the wavelength of this wave? b) Could this wavelength fit inside the dimensions of Room 411( room dimensions are roughly 11.5 m x 8.7 m)? Justify your answer with sound reasoningarrow_forwardSound is detected when a sound wave causes the eardrum to vibrate. Typically, the diameter of a human eardrum is around 8.4 mm. How much energy is delivered to your eardrum when someone whispers (20 dB) right next to your ear for 3.5 s?arrow_forwardProblem 5: The softest sound a human ear can hear is at 0 dB (Io = 10-12 W/m2). Sounds above 130 dB cause pain. A particular student's eardrum has an area of A = 56 mm2.Randomized Variables A = 56 mm2 Part (a) What is the most power, in watts, the ear can receive before the listener feels pain?Numeric : A numeric value is expected and not an expression.Pmax = __________________________________________Part (b) What is the smallest power, in watts, the ear can detect?Numeric : A numeric value is expected and not an expression.Pmin = __________________________________________arrow_forward
- Some studies suggest that the upper frequency limit of hearing is determined by the diameter of the eardrum. The wavelength of the sound wave and the diameter of the eardrum are approximately equal at this upper limit. If the relationship holds exactly, what is the diameter of the eardrum of a person capable of hearing 20 000 Hz? (Assume a body temperature of 37.0C.)arrow_forwardThe area of a typical eardrum is about 5.0 105 m2. Calculate the sound power (the energy per second) incident on an eardrum at (a) the threshold of hearing and (b) the threshold of pain.arrow_forwardBased on the graph in Figure 17.36, what is the threshold of hearing in decibels for frequencies of 60, 400, 1000, 4000, and 15,000 Hz? Note that many AC electrical appliances produce 60 Hz, music is commonly 400 Hz, a reference frequency is 1000 Hz, your maximum sensitivity is near 4000 Hz, and many older TVs produce a 15,750 Hz whine. Figure 17.36 The relationship of loudness in phons to intensity level (in decibels) and intensity (in watts per meter squared) for persons with normal hearing. The curved lines are equal-loudness curves—all sounds on a given curve are perceived as equally loud. Phons and decibels are defined to be the same at 1000 Hz.arrow_forward
- Why can a hearing test show that your threshold of hearing is 0 dB at 250 Hz, when Figure 17.37 implies that no one can hear such a frequency at less than 20 dB? Figure 17.37 The shaded region represents frequencies and intensity levels found in normal conversational speech. The O-phon line represents the normal hearing threshold, while those at 40 and 60 represent thresholds for people with 40- and 60-phon hearing losses, respectively.arrow_forwardThe human ear can detect a minimum intensity of Io = 10-12 W/m2, which has a sound intensity of 0 dB.Randomized Variablesβ = 25 dB If the student hears a sound at 25 dB, what is the intensity of the sound?Numeric : A numeric value is expected and not an expression.I = __________________________________________arrow_forwardAs discussed in the chapter, many species of bats find flying insects by emitting pulses of ultrasound and listening for the reflections. This technique is called echolocation. Bats possess several adaptations that allow them to echolocate very effectively. Although we can’t hear them, the ultrasonic pulses are very loud. In order not to be deafened by the sound they emit, bats can temporarily turn off their hearing. Muscles in the ear cause the bones in their middle ear to separate slightly, so that they don’t transmit vibrations to the inner ear. After an ultrasound pulse ends, a bat can hear an echo from an object a minimum of1 m away. Approximately how much time after a pulse is emitted is the bat ready to hear its echo?A. 0.5 ms B. 1 ms C. 3 ms D. 6 msarrow_forward
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