Calculadora de Bandas de Oitava
Calcule frequências centrais e limites de bandas de oitava e terço de oitava para análise acústica e medições de ruído.
Lower Band Edge
707.1068 Hz
Lower Band Edge vs Centre Frequency
Formula
Octave and Fractional-Octave Bands
Sound analysis often divides the spectrum into bands of constant percentage bandwidth.
Formulas
f_upper = f_c * 2^(1/(2N)) f_lower = f_c / 2^(1/(2N))
where N is the fraction denominator (1 for full octave, 3 for third-octave).
For a full octave band (N=1): f_upper/f_lower = 2 (one octave). For third-octave (N=3): the ratio is 2^(1/3) = 1.26.
Exemplo Resolvido
1000 Hz full octave band.
- 01f_upper = 1000 * 2^(1/2) = 1000 * 1.4142 = 1414.2 Hz
- 02f_lower = 1000 / 2^(1/2) = 1000 / 1.4142 = 707.1 Hz
- 03Bandwidth = 1414.2 - 707.1 = 707.1 Hz
Perguntas Frequentes
Why use octave bands instead of equal-width bands?
Our hearing perceives pitch logarithmically. Octave bands have constant percentage bandwidth, matching how we hear. Each band sounds equally wide.
What are the standard octave band centre frequencies?
31.5, 63, 125, 250, 500, 1000, 2000, 4000, 8000, and 16000 Hz. These are preferred frequencies defined in ISO standards.
Why are third-octave bands used?
They provide finer frequency resolution while maintaining the constant-percentage-bandwidth advantage. They are standard for building acoustics and noise regulations.
Aprender