1, Quick Measuring: Medical Grade Instant infrared Thermometer is suitable for kids, infants and adults, measurement speed is 1S, faster than conventional thermometers. This Infrared Thermometer adopts refined superior microchip and high sensitive sensor, make infrared thermometer high accurate and rapid no contact scan for people, objects and rooms
2, High Accurate Test Result: The infrared thermometer is Hospital Grade, measurement accuracy is ±0.2℃. Typical application in your home, clinic or workplace, bus, shops, schools, subway, library etc
3, Three measurement mode: The thermometer enables you to measure human, room or object temperature instantly with the press of a mode button. Perfect suits for parents, teachers, nurses, who want to keep a close eye on the body temperature of babies, children and patients.
4, Easy to Use: quiet scan temperature mode allows you to take instant scans of infants and children without a beeping noise. Celsius and Fahrenheit are easily and instantly switchable with an intuitive button.
5, Indicative Color: Temperature will be displayed on the LCD screen with clinically proven accuracy you can rely on. Three color backlight, green, orange, red, even easily readable in the dark.
5, FDA, CE, ISO certificates
Non Contact Thermometer, Infrared Thermometer,Non contact Baby Thermometer,COVID19 Axiswell Technology Co., Ltd , https://www.medhealthycare.com
Each instrument has its own unique spectrum and tone. To improve the ability of music appreciation, it is necessary to make more listening comparisons. When playing a piece of music, what is the difference between the sound produced by the speaker system and the sound of the actual instrument? How much? In order to make a hearing comparison, we should first understand some concepts of electroacoustic nouns, the auditory characteristics of the human ear, and the main technical parameters of the audio equipment.
I. Explanation of some electroacoustic terms
1. Pure tone: It has two meanings: (1) refers to the sound wave whose instantaneous sound pressure changes sinusoidally with time; (2) refers to the sound with a clear single tone.
2. Pitch: refers to the lowest frequency component of the composite sound.
3. Overtone: The component of the composite sound whose frequency is higher than the pitch, and its frequency may be an integral multiple of the fundamental frequency, or may not be. Various instruments can produce different harmonic components of different numbers and strengths with different playing methods, and even different pitches can be used even if the pitch is the same. Welcome to China Home Theater Network!
4. Acoustic wave: A mechanical wave propagating in an elastic medium, originating from the vibration of the sounding body. The sound wave range is 20Hz-20KHz, the sound wave with frequency higher than 20KHz is ultrasonic wave, the sound wave with frequency lower than 20Hz is the secondary sound wave, the ultrasonic wave and the infrasound wave generally cannot cause hearing, only the sound wave with frequency between them can be heard, we can listen The sound waves that arrive are called sound waves or audible sounds.
5. Sound field: refers to the area where the sound wave exists in the medium. Different sound sources and environments can form different sound fields.
6, loudness: also known as "volume", the human ear on the volume of a feeling. Depends on sound intensity, frequency and waveform.
7. Voice: Also known as "sound", it is mainly determined by the amount of homophonic sound and the relative amplitude of each homophonic sound.
Second, the auditory characteristics of the human ear
The human ear is sensitive to the orientation, loudness, pitch and tone of the sound, and there are large differences.
1. Sense of orientation: The human ear has a strong ability to distinguish the direction, distance and location of the sound. This auditory characteristic of the human ear is called "a sense of orientation."
2, the sense of loudness: for a small sound, as long as the loudness is slightly increased, the human ear can feel it, but when the sound level increases to a certain value, even if there is a larger increase, the human ear feels no significant change. . The audible sound is usually divided into three parts according to the multiplication relationship to determine the low, medium and high audio segments. That is: the bass band 20Hz-160Hz, the middle audio segment 160Hz-2500Hz, the high audio segment 2500Hz-20KHz.
3, timbre sense: refers to a special auditory comprehensive feeling of the human ear on the tone.
4. Focusing effect: The auditory characteristics of the human ear can be focused from a large number of sounds to a certain point. For example, when we listen to the symphony, we concentrate our energy and listening on the sound of the violin. The music played by other instruments will be suppressed by the cerebral cortex, making you feel the pure violin performance. This kind of inhibition ability varies from person to person, and people who often exercise listening exercise have strong inhibition ability. We call this auditory characteristic of the human ear a "focus effect." Doing more exercise in this area can improve the ability of the human ear to distinguish the tone, quality, resolution and level of a certain spectrum.
Third, the main technical indicators affecting sound quality, tone
1. Frequency range: The operating frequency bandwidth of the power amplifier under the specified distortion and rated output power, that is, the range between the lowest operating frequency of the power amplifier and the highest operating frequency. 2. Frequency response: The output gain of the power amplifier increases or decreases with the change of the input signal frequency and the phase lag changes with the input signal frequency. This indicator is the most important basis for assessing the quality of the power amplifier. The smaller the decibel value, the flatter the frequency response curve of the power amplifier, the smaller the distortion, and the stronger the degree of reproduction and reproducibility of the signal. Welcome to China Home Theater Network!
A good set of audio equipment, in addition to the reproduction of the sound of various instruments, but also the position, distance and scene of the various instruments played. Regardless of the color or model that the individual prefers, if the played sound is audibly different from the original instrument, it is not a good device. The true meaning of Hi-Fi is high reduction.
If your audio equipment can't restore the sound of the original instrument, then it can't be called high-fidelity equipment. When we use subjective hearing to judge a certain audio equipment, we must pay full attention to this point, and do not affect the correct judgment and discriminating ability due to personal preference.