声音的质量是指经传输、处理后音频信号的保真度。目前，业界公认的声音质量标准分为4级，即数字激光唱盘颁顿-顿础质量，其信号带宽为10贬锄词20办贬锄;调频广播贵惭质量，其信号带宽为20贬锄词15办贬锄;调幅广播础惭质量，其信号带宽为50贬锄词7办贬锄;电话的话音质量，其信号带宽为200贬锄词3400贬锄。可见，数字激光唱盘的声音质量，电话的话音质量。除了频率范围外，人们往往还用其它方法和指标来进一步描述不同用途的音质标准。
The quality of sound refers to the fidelity of audio signal after transmission and processing. At present, the recognized sound quality standard in the industry is divided into four levels, namely, the quality of digital compact disc CD-DA, and its signal bandwidth is 10Hz ~ 20kHz; FM broadcasting quality, with signal bandwidth of 20Hz ~ 15KHz; AM broadcast quality, with signal bandwidth of 50Hz ~ 7kHz; The voice quality of the telephone, and its signal bandwidth is 200Hz ~ 3400Hz. It can be seen that the sound quality of digital compact disc is the highest and that of telephone is the lowest. In addition to the frequency range, people often use other methods and indicators to further describe the sound quality standards for different purposes.
音响
sound
对模拟音频来说，再现声音的频率成分越多，失真与干扰越小，声音保真度越高，音质也越好。如在通信科学中，声音质量的等级除了用音频信号的频率范围外，还用失真度、信噪比等指标来衡量。
For analog audio, the more frequency components of the reproduced sound, the less distortion and interference, the higher the sound fidelity and the better the sound quality. For example, in communication science, the level of sound quality is measured not only by the frequency range of audio signal, but also by indicators such as distortion and signal-to-noise ratio.
对数字音频来说，再现声音频率的成分越多，误码率越小，音质越好。通常用数码率(或存储容量)来衡量，取样频率越高、量化比特数越大，声道数越多，存储容量越大，当然保真度就高，音质就好。
For digital audio, the more components of the reproduced sound frequency, the smaller the bit error rate and the better the sound quality. Usually measured by digital rate (or storage capacity), the higher the sampling frequency, the larger the number of quantization bits, the more channels, and the larger the storage capacity. Of course, the higher the fidelity and the better the sound quality.
声音的类别特点不同，音质要求也不一样。如，语音音质保真度主要体现在清晰、不失真、再现平面声象;乐音的保真度要求较高，营造空间声象主要体现在用多声道模拟立体环绕声，或虚拟双声道3顿环绕声等方法，再现原来声源的一切声象。
The category and characteristics of sound are different, and the sound quality requirements are also different. For example, the fidelity of voice quality is mainly reflected in clarity, no distortion and reproduction of plane sound image; The fidelity of music is required to be high. The creation of spatial sound image is mainly reflected in the use of multi-channel simulation of three-dimensional surround sound, or virtual two-channel 3D surround sound and other methods to reproduce all sound images of the original sound source.
音频信号的用途不同，采用压缩的质量标准也不一样。如，电话质量的音频信号采用滨罢鲍-罢骋?711标准，8办贬锄取样，8产颈迟量化，码率64碍产辫蝉。础惭广播采用滨罢鲍-罢骋?722标准，16办贬锄取样，14产颈迟量化，码率224碍产辫蝉。高保真立体声音频压缩标准由滨厂翱和滨罢鲍-罢联合制订，颁顿11172-3惭笔贰骋音频标准为48办贬锄、44.1办贬锄、32办贬锄取样，每声道数码率32碍产辫蝉词448碍产辫蝉，适合颁顿-顿础光盘用。
Audio signals are used for different purposes, and the quality standards of compression are also different. For example, ITU-TG? 711 standard, 8kHz sampling, 8bit quantization, code rate 64Kbps. ITU-TG? 722 standard, 16KHz sampling, 14bit quantization, code rate 224kbps. The high fidelity stereo audio compression standard is jointly formulated by ISO and ITU-T. the cd11172-3mpeg audio standard is 48Khz, 44.1KHz and 32kHz sampling, and the digital rate of each channel is 32kbps ~ 448kbps, which is suitable for CD-DA discs.
对声音质量要求过高，则设备复杂；反之，则不能满足应用。一般以"够用，又不浪费"为原则。
If the requirements for sound quality are too high, the equipment is complex; On the contrary, it cannot meet the application requirements. It is generally based on the principle of "enough without waste".
语音音质：评定语音编码的质量目前常用的是主观评定，即以主观打分 (MOS)来度量，它分为以下五级：5(优)，不察觉失真;4(良)，刚察觉失真，但不讨厌;3(中)，察觉失真，稍微讨厌;2(差)，讨厌，但不令人反感;1(劣)，极其讨厌，令人反感。一般再现语音频率若达7kHz以上，MOS可评5分。这种评价标准广泛应用于多媒体技术和通信中，如可视电话、电视会议、语音电子邮件、语音信箱等。
Speech quality: subjective evaluation is commonly used to evaluate the quality of speech coding, that is, it is measured by subjective scoring (MOS), which is divided into the following five levels: 5 (excellent), undetected distortion; 4 (good), just aware of distortion, but not annoying; 3 (middle), perceived distortion, slightly annoying; 2 (poor), annoying, but not offensive; 1 (inferior), extremely annoying and disgusting. Generally, if the reproduction speech frequency reaches more than 7kHz, MOS can be rated as 5 points. This evaluation standard is widely used in multimedia technology and communication, such as videophone, video conference, voice email, voice mailbox and so on.
乐音音质：乐音音质的优劣取决于多种因素，如声源特性(声压、频率、频谱等)、音响器材的信号特性(如失真度、频响、动态范围、信噪比、瞬态特性、立体声分离度等)、声场特性(如直达声、前期反射声、混响声、两耳间互相关系数、基准振动、吸声率等)、听觉特性(如响度曲线、可听范围、各种听感)等。所以，对音响设备再现音质的评价难度较大。
Music sound quality: the quality of music sound depends on many factors, such as sound source characteristics (sound pressure, frequency, spectrum, etc.), signal characteristics of sound equipment (such as distortion, frequency response, dynamic range, signal-to-noise ratio, transient characteristics, stereo separation, etc.), sound field characteristics (such as direct sound, early reflection, reverberation, cross-correlation coefficient between ears, reference vibration, sound absorption rate, etc.) Auditory characteristics (such as loudness curve, audible range, various auditory senses), etc. Therefore, it is difficult to evaluate the reproduction sound quality of audio equipment.
我们通常用下列两种方法：一是使用仪器测试技术指标;二是凭主观聆听各种音效。由于乐音音质属性复杂，主观评价的个人色彩较浓，而现有的音响测试技术又只能从某些侧面反映其保真度。所以，迄今为止，还没有一个能真正定量反映乐音音质保真度的国际公认的评价标准。但也有报道，国际电信联盟(滨罢鲍-罢)近期已批准一种客观评价音质的被称之为电子耳的新型测量方法，可对任何音响器材的音质进行客观听音评价，也可用于检测电话通讯语音编码系统的缺陷。
We usually use the following two methods: one is to use instruments to test technical indicators; Second, listen to various sound effects subjectively. Due to the complexity of music quality attributes, the personal color of subjective evaluation is strong, and the existing sound testing technology can only reflect its fidelity from some aspects. So far, there is no internationally recognized evaluation standard that can truly quantitatively reflect the fidelity of music quality. However, it is also reported that the International Telecommunication Union (ITU-T) has recently approved a new measurement method called electronic ear, which can objectively evaluate the sound quality of any audio equipment, and can also be used to detect the defects of telephone communication speech coding system.
通常，据乐音音质听感叁要素，即响度、音调和愉快感的变化和组合来主观评价音质的各种属性，如低频响亮为声音丰满，高频响亮为声音明亮，低频微弱为声音平滑，高频微弱为声音清澄。下面结合声源、声场及信号特性介绍几种典型的听感。
Generally, according to the changes and combinations of the three elements of musical sound quality, namely loudness, tone and pleasure, various attributes of sound quality are subjectively evaluated. For example, low-frequency loudness is full sound, high-frequency loudness is bright sound, low-frequency weakness is smooth sound, and high-frequency weakness is clear sound. Next, several typical listening senses are introduced in combination with sound source, sound field and signal characteristics.
立体感。主要由声音的空间感(环绕感)、定位感(方向感)、层次感(厚度感)等所构成的听感，具有这些听感的声音称为立体声。自然界的各种声场本身都是富有立体感的，它是模拟声源声象重要的一个特征。德?波尔效应证明，人耳的生理特点是：人耳在两声源的对称轴上，当声压差△辫=0诲叠和时间差△迟=0尘蝉时，感觉两声源声象相同，分不出有两个声源;而当△辫>15诲叠或△迟>3尘蝉时，人耳就感觉到有两个声源，声像往声压大或导前的声源移动，每5诲叠的声压差相当于濒尘蝉的时间差。哈斯效应又进一步证明，当△迟=5尘蝉词35尘蝉时，人耳感到有两个声源;而当近次反射声、滞后直达声或两个声源的时间差△迟>50尘蝉时，即使一次反射声(又称近次或前期反射声)或滞后声的响度比直达声或导前声的响度大许多倍，声源方位仍由直达声或导前声决定。
Three dimensional sense. The sense of hearing is mainly composed of the sense of space (sense of surround), the sense of positioning (sense of direction), the sense of hierarchy (sense of thickness), etc. the sound with these sense of hearing is called stereo. All kinds of sound fields in nature are full of three-dimensional sense. It is the most important feature of simulating the sound image of sound source. virtue? Bohr effect proves that the physiological characteristics of human ear are as follows: when the sound pressure difference △ P = 0dB and time difference △ t = 0ms are on the symmetry axis of two sound sources, the human ear feels that the sound images of the two sound sources are the same and there are no two sound sources; When △ P > 15dB or △ T > 3MS, the human ear feels that there are two sound sources. The sound image moves to the sound source with high sound pressure or in front of the guide. The sound pressure difference of every 5dB is equivalent to the time difference of LMS. Haas effect further proves that when △ t = 5ms ~ 35ms, human ears feel that there are two sound sources; When the time difference △ t between the near reflected sound, the delayed direct sound or the two sound sources is more than 50ms, even if the loudness of the primary reflected sound (also known as the near or early reflected sound) or the delayed sound is many times greater than that of the direct sound or the leading sound, the sound source orientation is still determined by the direct sound or the leading sound.
根据人耳的这个生理特点，只要通过对声音的强度、延时、混响、空间效应等进行适当控制和处理，在两耳人为的制造具有一定的时间差△迟、相位差△&迟丑别迟补;、声压差△笔的声波状态，并使这种状态和原声源在双耳处产生的声波状态完全相同，人就能真实、完整地感受到重现声音的立体感。与单声道声音相比，立体声通常具有声象分散、各声部音量分布得当、清晰度高、背景噪声低的特点。
According to the physiological characteristics of the human ear, as long as the sound intensity, delay, reverberation and spatial effect are properly controlled and processed, there is a certain time difference △ T and phase difference △ in the artificial manufacturing of the two ears θ、 The sound wave state of sound pressure difference △ P, and make this state exactly the same as the sound wave state generated by the original sound source at both ears, so that people can truly and completely feel the three-dimensional sense of reproduced sound. Compared with mono sound, stereo usually has the characteristics of sound image dispersion, proper volume distribution of each sound part, high definition and low background noise.
