Reducción de ruido
Para usar Reducción de ruido, necesita una región en la onda que contenga solo al ruido que desea reducir.
Tenga en cuenta que puede ser imposible conseguir una remoción satisfactoria cuando el ruido es muy fuerte, cuando es variable, cuando la música o voz no es mucho más fuerte que el ruido o cuando las frecuencias del ruido son muy similares a las de la música o voz.
Si su problema es principalmente murmullos o quejidos de todo agudo, el uso de un Filtro de muesca puede ayudar, lo que debiera ser realizado antes de aplicar Reducción de ruido.- Se accede por:
Paso 1 - Obtener el perfil de ruido
El primer paso le enseña a Audacity sobre el ruido que desea eliminar identificando el piso de ruido de las diferentes frecuencias que generan el ruido.
- Seleccione una región de la onda que contenga solo ruido. Un mínimo de 2048 muestras (0.05 seg. a una frecuencia de muestreo de 44100 Hz ) es necesario, menos que esto mostrará un error. Un perfil más largo es mejor. Si hay tipos de ruido muy diferentes en diferentes partes de la pista, es mejor tomar el perfil para el primer tipo, reducir su ruido, tomar el siguiente tipo y reducirlo, y así sucesivamente.
- Apriete .
- Apriete Obtener perfil de ruido.
Paso 2 - Reducir el ruido
- Select the entire region of onda from which you want to reduce the noise, then set the Noise Reduction parameters. This is often best done by trial and error, adjusting the sliders and using the Preview button to listen to a few seconds of audio after noise reduction. Listening to the Residue (the sound that will be filtered out when you apply "Reduce") can also be useful in determining how much damage is being done to the desired (non-noise) sound.
- Apriete .
- Noise Reduction (dB): Controls the amount of volume reduction to be applied to the identified noise. Use the lowest value that reduces the noise to an acceptable level. Higher values than necessary may make the noise even quieter, but will result in damage to the audio that remains.
- Sensitivity: Controls how much of the audio will be considered as noise, on a scale of 0 (off) to 24 (maximum). Greater sensitivity means that more noise will be removed, possibly at the expense of removing some of the desired signal as well. Lower values may result in the appearance of artifacts in the noise-reduced audio. Set this control to the lowest value that achieves effective noise removal without the introduction of artifacts.
- Frequency Smoothing (bands): At values of 1 or higher, this control spreads the noise reduction into the specified number of neighboring bands. This modifies the signal you were intending to keep, but if artifacts remain in the noise-reduced audio the smoothing can make those artifacts sound more acceptable. There is a chance that smoothing will make the desired audio less clear, so where your desired signal is strong and of wide frequency range and the noise is light, try leaving this control at 0 (off).
If you hear artifacts in the noise-reduced audio after setting Sensitivity as high as possible without eliminating desired audio, try setting Frequency Smoothing to a value between 1 and 6 bands. The width (in Hertz) of a frequency band is dependent on the sampling frequency of the track. Width = sampling frequency / 2048 = 21.53 Hz at 44100 Hz sampling rate.
Time smoothing is always applied by Noise Reduction (attack of 20 milliseconds and release of 100 milliseconds) but the settings are not configurable. Any frequency smoothing you request is applied after time smoothing.
- Noise:
- Reduce: Select this option to filter out the noise from the selection.
- Residue: Select this option to hear the sound that would be filtered out if you chose "Reduce". This is useful for finding the optimum settings that do not damage the audio. If you can hear recognizable bits of the desired sound in the residue, it is likely that you have set Noise Reduction too high or Sensitivity too high.
Los botones
Clicking on the command buttons give the following results:
- plays a short preview of what the audio would sound like if the effect is applied with the current settings, without making actual changes to the audio. The length of preview is determined by your setting in , the default setting is 6 seconds.
- applies the effect to the selected audio with the current effect settings.
- aborts the effect and leaves the audio unchanged.
Artifacts can happen if the noise floor is higher than was estimated, either because Sensitivity was set too low, or because the noise profile was not representative of the noise throughout the track. Although most of the noise will be suppressed most of the time, random artifacts may occur, which can be even more objectionable than the original noise. For a more technical explanation of artifacts, see How Audacity Noise Reduction Works in the Wiki.
Consejos
After creating a noise profile, CTRL + R or will apply Noise Reduction at its current settings.
Reducing noise usually results in some distortion. This is normal and there is nothing you can do about it. When there's only a little bit of noise, and the signal (that is, the voice, music or other desired sound) is much louder than the noise, this effect works well and there's very little audible distortion. Unfortunately, when the noise is very variable or very loud (the signal is not much louder than the noise) the result may be too distorted.
If you are still having problems the following tips may help.
- Select
Residuo from the Noise: options, click , listening for unwanted traces of the desired signal. You can usually reduce the amount of desired sound in the residue by decreasing Sensitivity or decreasing Noise Reduction.
- Decreasing Sensitivity decreases the chance of losing sound you want to keep (as indicated by hearing bits of the desired audio in the residue), but increases the chance of there being artifacts sounding like "tinkly bells" when applying the effect with Reducir selected.
- Decreasing Noise Reduction also decreases the chance of losing sound you want to keep (as indicated by hearing bits of the desired audio in the residue), but will increase the amount of noise remaining in the result when applying the effect with Reducir selected.
- Decreasing Sensitivity decreases the chance of losing sound you want to keep (as indicated by hearing bits of the desired audio in the residue), but increases the chance of there being artifacts sounding like "tinkly bells" when applying the effect with
- When you have found settings of Sensitivity and Noise Reduction that appear to do the least damage to the desired sound (based on there being little of that sound in the residue), click the Reducir radio button then click to apply the effect.
- Amplificar o normalizar puede ser realizado antes o después de la reducción de ruido.
- Do any Notch Filtering or Remoción de click before doing noise reduction.
- Do any compression or any other effects not mentioned above after doing noise reduction, not before.
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Al usar Reducción de ruido en cadenas el perfil es capturado como a continuación.
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Consejos avanzados
- Para una explicación más técnica sobre el algoritmo usado en Reducción de ruido, vea Algoritmo de Reducción de ruido en la Wiki.
- También vea Procedimiento de ejemplo para digitalización de LP ya que lista algunos programas alternativos para reducción de ruido que puede usar como parte de su rutina de restauración de audio.
Limitaciones
- Tomar un perfil de ruido en una muestra a una frecuencia de muestro y remover el ruido en otra pista a una frecuencia diferente producirá resultados pobres y por ello está prohibido con un error "La frecuencia de muestreo del perfil de ruido debe coincidir con la del sonido a procesar".
- Tomar un perfil de ruido de dos o más pistas a frecuencias de muestreo diferentes es prohibido con un error "Todos los datos de Perfil de ruido deben tener la misma frecuencia de muestreo".
