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The sampling rate is the frequency at which the original sound is sampled per unit time, and the higher the frequency, the closer it is to the waveform of the real sound, but 32kHz is enough for the average user.

The waveform is a sound wave"Amplitude - time"Figure, Qianqian can listen quietly.

A spectrogram is a spectrogram that is the sound of a certain moment"Frequency - Amplitude"Figure, Qianqian Jing can also listen.

Sound processing software can view at least one of the above two graphs) The energy spectrum is physically possible, and it is sound waves"Energy-time"figure, I don't know if there is such software.

I haven't used this software, I've used it, it's not good, the effect is too little.

Later, I used Adobe Audition, and the waveform can be zoomed in, and the sampling rate can be set by myself, but it is limited by the hardware (such as a sound card or other sampling device).

What is sample rate.

The frequency corresponds to the time axis, and the amplitude corresponds to the level axis. Waves are infinitely smooth, strings can be seen as being made up of an infinite number of points, and since storage space is relatively limited, the points of the strings must be sampled during digital encoding. The process of sampling is to extract the frequency value of a certain point, obviously, the more points extracted in one second, the more abundant frequency information obtained, in order to restore the waveform, in a vibration, there must be 2 points of sampling, the highest frequency that the human ear can feel is 20kHz, so to meet the hearing requirements of the human ear, it is necessary to take at least 40k samples per second, expressed in 40kHz, this 40kHz is the sampling rate.

The higher the values of the sample rate and sample size, the closer the recorded waveform is to the original signal.

It is recommended to use cool, which can be found on the Internet, very good sound processing and recording software.

Categories: Medical Diseases.

Problem description: How does a hearing aid work and what are the main performance indicators? What has been the popularity of hearing aids in the past few years? What is the reason for this change?

Analysis: There are many names for hearing aids, but all electronic hearing aids work the same. Any hearing aid consists of 6 basic structures.

1 Microphone (microphone or microphone) takes sound and converts it into radio waves, i.e., converts sound energy into electrical energy.

2 Amplifier - amplify electrical signals.

3 Headset - (receiver) converts electrical signals into acoustic signals (i.e. converts electrical energy into sound energy).

4 Earmolds (earbuds) are placed in the external ear canal.

5 Volume control switch.

6 Power supply – dry cell battery for amplifier.

Key Performance Indicators:

Maximum sound output.

Maximum sound gain.

Distortion. Noise.

1.Maximum sound outputThis refers to the maximum amount that the hearing aid can amplify sound, also known as saturated sound output. Internationally, hearing aids are divided into five categories according to this amount:

A - below 105 decibels.

b - 105 114 dB.

c - 115 124 dB.

D - 125 134 dB.

E - 135 dB or more.

The sound intensity of the hearing aid volume output of 105 decibels is equivalent to the noise level of the textile workshop, and 135 decibels is equivalent to the noise level of the gun, such a strong sound is extremely harmful to people with normal hearing, but for the deaf person, such a volume is not significant after deducting the hearing loss value of his deafness level.

2.Maximum Sound Gain: This refers to the ability of the hearing aid to amplify the sound it receives. This amount is usually in the range of 40 to 70 decibels.

For example, if a mother emits about 70 decibels of sound to her child's storyteller, and her child is assumed to be moderately deaf and has a hearing loss of 6o decibels, then the child can only hear 10 decibels 7o decibels to 6o decibels. This number was too small for the call, so he couldn't understand what his mother was saying. Suppose the child is given a hearing aid with a gain of 55 decibels, and the mother's voice can be raised to (55 dB 10 lo dB = ) 65 decibels, so that the intensity of the sound can make it convenient for him to talk.

3.Distortion: It is used to measure the fidelity of a hearing aid to a sound. If the distortion of the sound amplified by the hearing aid does not exceed 3%, we will feel that the sound is quite natural. If the distortion exceeds 10 percent, the sound will not be the same as the original, so the sound quality in this case is not ideal.

4.Noise, in this case, refers to the noise generated by the hearing aid amplifier circuit itself. Disturbing useful sound occurs when the noise is close to within 1o decibels of the desired sound.

Therefore, a good hearing aid should be less noisy. Internationally, a name called "equivalent input noise" is used to measure it, and it is generally required that this indicator should reach below 35 decibels.

丨x+y-2 3丨 is the opposite of xy-1.

丨x+y-2 3丨+ xy-1=0

丨x+y-2 3丨 0

x+y-2√3≥0

xy-1≥0

xy-1≥0

丨x+y-2 3丨+ xy-1=0

x+y-2√3=0

xy-1=0

Solution x = 3 2

y=√3±√2

Finance is a discipline that studies value judgments and the law of value. Finance is a discipline that is differentiated from economics and studies financial integration, mainly including four major academic professional fields: banking, science, insurance, and trust.

Cultivation goals. This major cultivates high-quality compound professionals with both ability and political integrity who have broad theoretical knowledge and professional skills in finance, and can not only study for graduate degrees in universities and research institutes at home and abroad, but also work in financial institutions such as banks, trusts, investments, insurance, and other enterprises, and management departments.

Should have the ability.

Students in this major will be able to fully grasp the basic theories and basic knowledge of economics and finance. Systematically master the basic theories and analytical methods, professional knowledge and business skills of finance; Familiarity with relevant laws, policies and international rules; Understand the history, current situation and development trend of financial disciplines and financial industry at home and abroad; Have strong ability to investigate, analyze, solve practical problems and have certain scientific research ability; Proficient in a foreign language, with strong foreign language application ability, able to use foreign language to obtain professional information; Be proficient in using modern information tools to engage in professional work.

Curriculum. Major courses: Microeconomics, Macroeconomics, Accounting, Econometrics, International Economics, Finance, Financial Intermediation, Financial Markets, Commercial Bank Management, Financial Engineering, International Finance, Corporate Finance, Banking, Insurance, Investment, Financial Statistical Analysis, Investment Banking, International Settlement, Marketing, Financial Law, Asset Valuation, Project Valuation, and Options.

Direction of employment. Financial industry regulatory departments, various banks, credit cooperatives, insurance companies, trust institutions, asset management companies, listed companies, universities or research institutes and other financial institutions are engaged in financial industry work or teaching and scientific research.

Difficult and not difficult are relative, it is easy to do, and difficult not to do. The most important thing is whether this major is suitable for you, whether you like this major and its future employment direction.