Sound
Decibels are the units of measurement used to describe voltage and power levels. The abbreviation for a decibel is dB (Sauvala). Some decibel comparisons are: 10 dB is about as loud as someone whispering, 70 dB is a shouted conversation, and 110 dB is as loud as a jet engine ("Sound"). Decibels are the expressions of ratios. Some formulas for decibels are power =10log(P1/P2)(P1= power 1 and P2= power 2) and voltage =20log(v2/v1)(V2= voltage 2, V1= voltage 2) (jgoldste@wyoming.com). Decibels are measured by 6's. For example, 6 dB is twice the original value (0 dB) and -6dB is ½ of the original value (0 dB) (Sauvala). O dB is the minimum a human can hear and 140 dB is the threshold of pain for a human (Freedom). Decibel means the measurement is a ratio measured on a logarithmic scale and whenever you add 6 dB the voltage doubles (BBC Online). The average human ear cannot notice decibel changes of less than one decibel (malcolm@mcs.net). Every time the distance from a sound source doubles, there is a drop of 6 dB and the formula for this is DC= 20log(distance1/distance2) (DC= decibels of change). You round decibels to the ones place (Mc Squared System Design Group).
There is only one decibel system, but there are two ways to express values--power decibels and voltage decibels. Power decibels are used to express sound pressure levels and power amp and speaker specifications. They are used for equipment that translates signals back to sound and to someone's ears for hearing. Voltage decibels are used to express gain, loss, levels, noise, and line equipment specifications. These are used in most equipment that pick up sounds, converts them to electrical signals and sends them from one point to another. Both of these can be converted to each other. If you have power dB all you have to do is double it to get voltage dB and if you have voltage dB than you take half of that for power dB (malcolm@mcs.net).
Sound has three measurable parts: frequency, amplitude, and duration. Frequency is the rate of vibration that determines how high or low the pitch is. "Amplitude is the magnitude of the vibration, which determines how loud the sound is."(Freedom) Duration is how long the sound lasts, measured in seconds.
The purpose of this experiment was to determine whether if the sound is affected when it travels through different length pipes. The method used to do this experiment was created by using 5 different PVC pipes in the lengths of 10, 20, 30, 40, and 50 centimeters. Then, using a tuning fork, sound will be produced on one end of the PVC pipe and measured with a decimeter on the other end. This experiment was recorded using 5 trials for each independent level and the average decibels (dB) for each pipe length were recorded.
The unit used to measure the intensity of sound is called the decibel(dB). Sounds that measure up to 75dB are considered to be in the "safe zone". Constant exposure to to sound at these levels are very unlikely to cause any lasting damage to long term hearing. The sound of regular volume conversation measures at around 60dB and the sound of a running dishwasher measures at roughly 75dB. Sounds around the 85dB level are considered a moderate risk to hearing. Exposure at these levels for extened periods of time may lead to some form of damage causing NIHL. Sounds at these levels include heavy traffic and crowded areas at 85dB, active subway stations at 95dB and listening to an mp3 player with ear buds at maximum volume at 105dB in which listening for just 15 minutes can cause permanent damage. Sound at 120dB and above are in the "danger zone". This level of sound is to be avoided at all cost as exposure even for a short pulse will lead to immediate permanent damage. This level includes the sound of ambulance sirens at 120dB, a jet taking off at 140dB and gunshots at 165 dB and above. (Rabinowitz,
At any point in the air near the source of sound, the molecules are moving backwards and forwards, and the air pressure varies up and down by very small amounts. The number of vibrations per second is called the frequency which is measured in cycles per second or Hertz (Hz). The pitch of a note is almost entirely determined by the frequency: high frequency for high pitch and low for low .
Despite the increased emphasis on the need for noise reduction, studies published in the past five years found that sound levels in the ICU continue to exceed the WHO noise recommendations.3, 5-10 To interpret research on noise in the hospital, it is important to have an understanding of the terminology used (Table 1.) Noise is simply unwanted sound. What is noise to one individual may not be to another. Sound levels are reported in decibels (dB), with 0 dB being the threshold for human hearing. A 3 dB change in sound level is just discernible, a 5 dB change is discernible and a 10 dB change is perceived as a doubling or halving of the sound level....
Noise is ubiquitous in our environment. (Pediatrics , 1997) It is undesirable sound, unwanted sound. Sound is what we hear. It is vibration in a medium, usually air. Sound has intensity, frequency and duration. The ability to hear sounds at certain frequencies is more readily lost in response to noise. (Pediatrics , 1997). The further you are from sound the less effect you hear it but the more closer you are to sound the louder it is.
Sound is a wave, which can change in pitch according to changing air pressure. It is produced by the vibrations of objects. Waves can be measured by speed (v), frequency (f), wavelength (λ), and period. The frequency of a wave describes how many cycles of a wave occur per unit time. A sound with a high frequency has more wavelengths in a set amount of time than a sound with a low frequency. High frequencies have smaller wavelengths, and low frequencies have larger wavelengths. The higher frequency, the higher the perceived pitch. The wavelength, frequency, and speed are all related by the equation: v = fλ. They can also be used in the equation: f = v/λ.
The amount of damage resulting from noise exposure depends on the intensity level of the noise in relation to the length of time exposed to the noise. According to NIOSH, sound levels that exceed a time weighted average of 85 decibels dB(A) over an 8-hour period of time are considered dangerous. It is recommended that exposure time be decreased by half for every 3 dB increase in intensity that exceeds 85 dB because noise exposure increases with time and intensity (NIOSH, 1998). Impulse sounds such as gun fires or firecrackers can exceed 150 dB(A) and cause immediate, irreversible, sensorineural hearing loss (Axelsson & Jerson, 1985). Most people are unaware of the decibel system and how much 85 dB equates to, but according to the article, “How loud is too loud? Minimize noise exposure to protect your hearing”, if someone has to yell to be heard, it is probably loud enough to cause hearing damage, (Johnson, 2011).
Sound travels in the shape of a wave. There are two types of sound waves, longitudinal and transverse [9]. Longitudinal waves travel parallel to the source of the wave and transverse waves travel perpendicular to the source of the wave. Sound is produced from vibrations through a medium, and travels in the form of longitudinal waves [10]. Pitch is the general perception of the highness or lowness of a sound which depends on the frequency complexity, and loudness of the sound [11]; on the other hand, in music pitch related to notes that are being played. The vibrations caused from a disturbance such as a vibrating string create areas of compression and rarefaction of the molecules in the medium that the vibrations are traveling through. Sound is only produced when these vibrations are traveling through a medium. An observer is able to hear sounds because these areas of compression and rarefaction are picked up by the observer's ears, and translated to the brain from longitudinal sound waves. Figure 5 [12] (middle-left) shows the areas of compression and rarefaction in the air in a hollow tube caused by the vibrations from a tuning fork. Compressions are areas of with a high density of molecules; whilst, rarefactions are areas with a low density of
This lab experiment was conducted in order to test the speed of sound, which is the distance traveled per unit time by a sound wave. This experiment was carried out with a certain setup, which involved materials such as a computer, a Logger Pro, a vernier microphone, two tubes, a temperature probe, a meter stick, and a dog trainer clicker. These materials were set up in a specific fashion, the Logger Pro was connected to the computer, which allowed for a temperature reading. The microphone was then connected to the lab interface and the two tubes were taped together from one end. One end of the tube was then placed against a wall, the microphone positioned near the open end of the tube as the dog clicker was pressed. Once the clicker was pressed, the speed of the sound traveling through the tube was collected by the microphone, the data then was inputted into the computer by the Logger Pro.
In mathematics, a metric conversion formula is one of the important topics. It is used for calculating purpose of an international decimalized system of measurement. In all over world, metric conversion formulas are the most common system for calculating different types of units. For personal, commercial and scientific purposes, this can be used widely. From the base units of conversions can be derived from larger and smaller units which may be standard set of prefixes in powers of ten.
as Hertz (Hz). The sounds of speech are in the range of 250 Hz to 4000
The main reason the metric system is known for its simplicity is because there is only unit of measurement or a base unit for each type of measured quantity measured; length mass, weight, etc… There are a few base units in the metric system but the most common ones which are used are the meter, gram and liter. As an example if ...
As a musician, I always related to sounds in terms of musical application. The only sounds I paid attention to were those involved in creating and performing music. Musical sounds were the most important to me. Well . . . actually, as a traveling musician, any troubling sounds my car made were almost as important. The only other sound I appreciated was silence - something I valued after six nights of rhythmic and melodic saturation and the babble of three hundred or so party drunks.
Each of the senses receives a different stimulus that allows us to perceive that specific type of information. For hearing the stimulus is sound waves. These are waves of pressure that are conducted through a medium (Martini, 2009). Often this medium is air but it can also be water or a solid object. Each wave consists of a region where the air molecules are gathered together and an opposite region where they are farther apart (Martini, 2009). A wavelength is the distance between either two wave peaks or two wave troughs. The number of waves that pass through a fixed reference point in a given time is the frequency. High pitch sounds have a high frequency where as low pitch sounds have a low frequency (Myers, 2010). The amplitude is the amount of energy, or intensity, in a sound wave. The more energy that a sound wave has, the louder it seems. For us to perceive any of the sound waves around us, they must pass through the external, middle, and inner ea...
What distinguishes sound waves from most other waves is that humans easily can perceive the frequency and amplitude of the wave. The frequency governs the pitch of the note produced, while the amplitude relates to the sound le...