Building Module

This module provides functions related to building acoustics.

API Documentation

The building module contains functions for calculating acoustic properties of building elements, including sound transmission class (STC) and weighted sound reduction index (\(R_w\)) calculations.

FUNCTION	DESCRIPTION
rw_curve	Calculate the reference curve for weighted sound reduction index.
rw	Calculate the weighted sound reduction index (\(R_w\)).
rw_c	Calculate the weighted sound reduction index with spectrum adaptation term C (\(R_w + C\)).
rw_ctr	Calculate the weighted sound reduction index with spectrum adaptation term \(C_{tr}\) (\(R_w + C_{tr}\)).
stc_curve	Calculate the Sound Transmission Class (STC) reference curve.
stc	Calculate the Sound Transmission Class (STC).
mass_law	Calculate transmission loss according to mass law.

Functions

rw_curve

rw_curve(tl: NDArray[float64]) -> NDArray[float64]

Calculate the curve of \(Rw\) from a NumPy array tl with third octave data between 100 Hz and 3.15 kHz.

PARAMETER	DESCRIPTION
tl	Transmission Loss TYPE: NDArray[float64]

RETURNS	DESCRIPTION
NDArray[float64]	NDArray[np.float64]: Reference curve values.

Source code in acoustic_toolbox/building.py

def rw_curve(tl: NDArray[np.float64]) -> NDArray[np.float64]:
    """Calculate the curve of $Rw$ from a NumPy array `tl` with third
    octave data between 100 Hz and 3.15 kHz.

    Args:
        tl: Transmission Loss

    Returns:
        NDArray[np.float64]: Reference curve values.
    """
    ref_curve = np.array([0, 3, 6, 9, 12, 15, 18, 19, 20, 21, 22, 23, 23, 23, 23, 23])
    residuals = 0
    while residuals > -32:
        ref_curve += 1
        diff = tl - ref_curve
        residuals = np.sum(np.clip(diff, np.min(diff), 0))
    ref_curve -= 1
    return ref_curve

rw

rw(tl: NDArray[float64]) -> float

Calculate \(R_W\) from a NumPy array tl with third octave data between 100 Hz and 3.15 kHz.

PARAMETER	DESCRIPTION
tl	Transmission Loss. TYPE: NDArray[float64]

RETURNS	DESCRIPTION
float	The weighted sound reduction index. TYPE: float

Source code in acoustic_toolbox/building.py

def rw(tl: NDArray[np.float64]) -> float:
    """Calculate $R_W$ from a NumPy array `tl` with third octave data
    between 100 Hz and 3.15 kHz.

    Args:
        tl: Transmission Loss.

    Returns:
        float: The weighted sound reduction index.
    """
    return rw_curve(tl)[7]

rw_c

rw_c(tl: NDArray[float64]) -> float

Calculate \(R_W + C\) from a NumPy array tl with third octave data between 100 Hz and 3.15 kHz.

PARAMETER	DESCRIPTION
tl	Transmission Loss. TYPE: NDArray[float64]

RETURNS	DESCRIPTION
float	The weighted sound reduction index with spectrum adaptation term C. TYPE: float

Source code in acoustic_toolbox/building.py

def rw_c(tl: NDArray[np.float64]) -> float:
    """Calculate $R_W + C$ from a NumPy array `tl` with third octave data
    between 100 Hz and 3.15 kHz.

    Args:
        tl: Transmission Loss.

    Returns:
        float: The weighted sound reduction index with spectrum adaptation term C.
    """
    k = np.array(
        [-29, -26, -23, -21, -19, -17, -15, -13, -12, -11, -10, -9, -9, -9, -9, -9]
    )
    a = -10 * np.log10(np.sum(10 ** ((k - tl) / 10)))
    return a

rw_ctr

rw_ctr(tl: NDArray[float64]) -> float

Calculate \(R_W + C_{tr}\) from a NumPy array tl with third octave data between 100 Hz and 3.15 kHz.

PARAMETER	DESCRIPTION
tl	Transmission Loss. TYPE: NDArray[float64]

RETURNS	DESCRIPTION
float	The weighted sound reduction index with spectrum adaptation term \(C_{tr}\). TYPE: float

Source code in acoustic_toolbox/building.py

def rw_ctr(tl: NDArray[np.float64]) -> float:
    """Calculate $R_W + C_{tr}$ from a NumPy array `tl` with third octave
    data between 100 Hz and 3.15 kHz.

    Args:
        tl: Transmission Loss.

    Returns:
        float: The weighted sound reduction index with spectrum adaptation term $C_{tr}$.
    """
    k_tr = np.array(
        [-20, -20, -18, -16, -15, -14, -13, -12, -11, -9, -8, -9, -10, -11, -13, -15]
    )
    a_tr = -10 * np.log10(np.sum(10 ** ((k_tr - tl) / 10)))
    return a_tr

stc_curve

stc_curve(tl: NDArray[float64]) -> NDArray[float64]

Calculate the Sound Transmission Class (STC) curve from a NumPy array tl with third octave data between 125 Hz and 4 kHz.

PARAMETER	DESCRIPTION
tl	Transmission Loss. TYPE: NDArray[float64]

RETURNS	DESCRIPTION
NDArray[float64]	NDArray[np.float64]: The STC reference curve values.

Source code in acoustic_toolbox/building.py

def stc_curve(tl: NDArray[np.float64]) -> NDArray[np.float64]:
    """Calculate the Sound Transmission Class (STC) curve from a NumPy array `tl`
    with third octave data between 125 Hz and 4 kHz.

    Args:
        tl: Transmission Loss.

    Returns:
        NDArray[np.float64]: The STC reference curve values.
    """
    ref_curve = np.array([0, 3, 6, 9, 12, 15, 16, 17, 18, 19, 20, 20, 20, 20, 20, 20])
    top_curve = ref_curve
    res_sum = 0
    while True:
        diff = tl - top_curve
        residuals = np.clip(diff, np.min(diff), 0)
        res_sum = np.sum(residuals)
        if res_sum < -32:
            if np.any(residuals > -8):
                top_curve -= 1
                break
        top_curve += 1
    return top_curve

stc

stc(tl: NDArray[float64]) -> float

Calculate the Sound Transmission Class (STC) from a NumPy array tl with third octave data between 125 Hz and 4 kHz.

PARAMETER	DESCRIPTION
tl	Transmission Loss. TYPE: NDArray[float64]

RETURNS	DESCRIPTION
float	The Sound Transmission Class value. TYPE: float

Source code in acoustic_toolbox/building.py

def stc(tl: NDArray[np.float64]) -> float:
    """Calculate the Sound Transmission Class (STC) from a NumPy array `tl` with
    third octave data between 125 Hz and 4 kHz.

    Args:
        tl: Transmission Loss.

    Returns:
        float: The Sound Transmission Class value.
    """
    return stc_curve(tl)[6]

mass_law

mass_law(
    freq: float | NDArray[float64],
    vol_density: float,
    thickness: float,
    theta: float = 0,
    c: float = 343,
    rho0: float = 1.225,
) -> float | NDArray[float64]

Calculate transmission loss according to mass law.

PARAMETER	DESCRIPTION
freq	Frequency of interest in Hz. TYPE: float | NDArray[float64]
vol_density	Volumetric density of material in \(frac{kg}{m^3}\). TYPE: float
thickness	Thickness of wall in m. TYPE: float
theta	Angle of incidence in degrees. Default value is 0 (normal incidence). TYPE: float DEFAULT: 0
c	Speed of sound in m/s. Defaults to 343. TYPE: float DEFAULT: 343
rho0	Density of air in \(\frac{kg}{m^3}\). Defaults to 1.225. TYPE: float DEFAULT: 1.225

RETURNS	DESCRIPTION
float | NDArray[float64]	float | NDArray[np.float64]: Transmission loss value(s) in dB.

Source code in acoustic_toolbox/building.py

def mass_law(
    freq: float | NDArray[np.float64],
    vol_density: float,
    thickness: float,
    theta: float = 0,
    c: float = 343,
    rho0: float = 1.225,
) -> float | NDArray[np.float64]:
    r"""Calculate transmission loss according to mass law.

    Args:
        freq: Frequency of interest in Hz.
        vol_density: Volumetric density of material in $frac{kg}{m^3}$.
        thickness: Thickness of wall in m.
        theta: Angle of incidence in degrees. Default value is 0 (normal incidence).
        c: Speed of sound in m/s. Defaults to 343.
        rho0: Density of air in $\frac{kg}{m^3}$. Defaults to 1.225.

    Returns:
        float | NDArray[np.float64]: Transmission loss value(s) in dB.
    """
    rad_freq = 2.0 * np.pi * freq
    surface_density = vol_density * thickness
    theta_rad = np.deg2rad(theta)
    a = rad_freq * surface_density * np.cos(theta_rad) / (2 * rho0 * c)
    tl_theta = 10 * np.log10(1 + a**2)
    return tl_theta