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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Chapter 17 Solutions
Physics for Scientists and Engineers with Modern Physics
- Sound 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_forwardAn inter-spike interval (ISI) histogram is constructed based on neural responses to a pure tone. Three peaks are observed on the ISI histogram and they are at 4, 8, and 12 ms. What is the tonal frequency? 500 Hz 2000 Hz 1000 Hz Ⓒ250 Hzarrow_forward
- Problem 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_forwardSome 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_forward
- Based 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_forwardWhy 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_forwardAs you zip through space in your PPS (personal propulsion suit), your pulse rate as you count it is 119 bpm (beats per minute). This high pulse rate serves as objective evidence of your excitement. However, an observer on the Moon, an expert in pulse rate telemetry, measures your pulse rate as slower. In fact, she detects only 0.591 times the rate you count and claims that you must be pretty calm in spite of everything that is going on. How fast are you moving with respect to the Moon? speed relative to the Moon: m/sarrow_forward
- There was an accident and NASA engineers are trying to sort out where two of their Mars Rovers (named 'Tango' and 'Foxtrot') have landed. The engineers know that landing site A is much hotter than landing site B. Unfortunately, the only working sensors on Tango and Foxtrot measure the speed of sound. If Tango measures the speed of sound at its landing site as 240 m/s, while Foxtrot measures speed of sound as 258 m/s at its landing site, where has each rover landed? Tango landed at site A while Foxtrot landed at site B. Tango landed at site B while Foxtrot landed at site A. Both Tango and Foxtrot landed at site A. O Both Tango and Foxtrot landed at site B.arrow_forwardYour experiments on a particular insulator indicate that at 20°C, the average speed of sound in the insulator is vi = 8500 m/s and its bulk modulus is Bi = 370 GPa. Experimental results from your colleague show that a certain metal alloy has a density of ρm = 6500 kg/m3 and a bulk modulus of Bm = 110 GPa. a. Calculate the density of the insulator ρi in kilograms per cubic meter. b. Calculate the speed of sound vm in the metal alloy in meters per second. c. If the sound traveled as indicated in the structure in figure 1, emerging from the insulator at time ti and the alloy at time tm, determine Δt = tm - ti in seconds. The length of the structure is L = 1.0 m. d. Find the total amount of time t, in seconds, it takes to travel through the structure as indicated in figure 2. The length of the structure is L = 1.0 m.arrow_forwardAlthough 0 dB is often referred to as the lower threshold of human hearing, it is important to realize that the human ear is not equally sensitive to all frequencies of sound. In other words, a particular noise may sound louder or softer depending on the frequency of the sound wave being transmitted. Because of this variation, scientists have defined a unit of loudness, called a phon, to represent the intensity of sound waves with a frequency of 1000 Hz: A 60-phon sound is one that is perceived by the human ear to have the same loudness as a sound wave with an intensity of 60 dB and a frequency of 1000 Hz. Figure Intensity (in dB) 100 80 60 40 20 0 30 50 100 500 100 phons 80 phons 60 phons 40 phons 20 phons 0 phons 000'I Frequency (in Hz) 000'S 10,000 1 of 1 There is no simple mathematical formula for converting phons into decibels. The relationship between these two measures of intensity has been determined by experiment. The graph (Figure 1) displays the perceived loudness of sound…arrow_forward
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