Indent your code with a PEP8-compliant IDE or linter; it's a perfect mess right now.

Move your global code into functions and maybe classes. There are two good use cases for classes here - one for a GUI and one for an audio processor.

offset must not be aStringVar, but instead anIntVar - among other reasons this will obviate the cast inint(offset.get()). Do not leave it nameless and do not leave it orphaned; its parent needs to be the root object.

Move your import ofbilinear up to join your other imports.

Your imports should avoidimport *; that makes a vast swamp out of the global namespace and it doesn't need to be like that. Traditionallynumpy is aliased tonp.

Consider writing a context manager to close off your audio stream.

numpy.absolute(a)**2 is justa**2, right?

Deleteupdate_max_if_new_is_larger_than_max. This is just a call to the built-inmax().

Rather than

         if new_decibel>85:             led.to_red(on=True)         else:             led.to_red(on=False)

just move the boolean expression to the argument of a single call and delete theif.

Add PEP484 typehints.

Convert your lists inA_weighting into immutable tuples.

Listen to the warnings being told to you: your use ofnp.fromstring needs to be replaced withnp.frombuffer.

str(int(float(str(max_decibel)))) is just... majestic. Use a formatting string instead.

As @Seb comments, 44300 should almost certainly be 44100.

polymul isdeprecated. UsePolynomial instead.

An equivalent torms_flat is the more integrated and maybe faster

np.linalg.norm(a) / np.sqrt(len(a))

which, based onthelinalg source, further reduces to a self-dot-product:

np.sqrt(a.dot(a) / len(a))

Suggested

import tkinter as tkimport numpy as npimport pyaudioimport tk_toolsfrom numpy.polynomial import Polynomialfrom scipy.signal import bilinear, lfilterCHUNKS = [4096, 9600]CHUNK = CHUNKS[1]FORMAT = pyaudio.paInt16CHANNEL = 1RATES = [44100, 48000]RATE = RATES[1]def A_weighting(fs: float) -> tuple[np.ndarray, np.ndarray]:    f1 = 20.598997    f2 = 107.65265    f3 = 737.86223    f4 = 12194.217    a1000 = 1.9997    nums = Polynomial(((2*np.pi * f4)**2 * 10**(a1000 / 20), 0,0,0,0))    dens = (        Polynomial((1, 4*np.pi * f4, (2*np.pi * f4)**2)) *        Polynomial((1, 4*np.pi * f1, (2*np.pi * f1)**2)) *        Polynomial((1, 2*np.pi * f3)) *        Polynomial((1, 2*np.pi * f2))    )    return bilinear(nums.coef, dens.coef, fs)def rms_flat(a: np.ndarray) -> float:    return np.sqrt(a.dot(a) / len(a))class Meter:    def __init__(self) -> None:        self.pa = pyaudio.PyAudio()        self.stream = self.pa.open(            format=FORMAT,            channels=CHANNEL,            rate=RATE,            input=True,            frames_per_buffer=CHUNK,        )        self.numerator, self.denominator = A_weighting(RATE)        self.max_decibel = 0    def __enter__(self) -> 'Meter':        return self    def __exit__(self, exc_type, exc_val, exc_tb) -> None:        self.stream.stop_stream()        self.stream.close()        self.pa.terminate()    def listen(self, offset: int) -> float:        block = self.stream.read(CHUNK)        decoded_block = np.frombuffer(block, dtype=np.int16)        y = lfilter(self.numerator, self.denominator, decoded_block)        new_decibel = 20*np.log10(rms_flat(y)) + offset        self.max_decibel = max(self.max_decibel, new_decibel)        return new_decibelclass GUI:    def __init__(self, meter: Meter) -> None:        self.meter = meter        self.root = root = tk.Tk()        root.title('Decibel Meter')        root.grid()        root.protocol('WM_DELETE_WINDOW', self.close)        self.app_closed = False        self.gaugedb = tk_tools.RotaryScale(root, max_value=120, unit=' dBA')        self.gaugedb.grid(column=1, row=1)        self.led = tk_tools.Led(root, size=50)        self.led.grid(column=3, row=1)        self.led.to_red(on=False)        tk.Label(root, text='Too Loud').grid(column=3, row=0)        tk.Label(root, text='Max').grid(column=2, row=0)        tk.Label(root, text='Calibration (dB)').grid(column=4, row=0)        self.maxdb_display = tk_tools.SevenSegmentDigits(root, digits=3, digit_color='#00ff00', background='black')        self.maxdb_display.grid(column=2, row=1)        self.offset = tk.IntVar(root, value=0, name='offset')        spinbox = tk.Spinbox(root, from_=-20, to=20, textvariable=self.offset, state='readonly')        spinbox.grid(column=4, row=1)    def close(self) -> None:        self.app_closed = True    def run(self) -> None:        while not self.app_closed:            new_decibel = self.meter.listen(self.offset.get())            self.update(new_decibel, self.meter.max_decibel)            self.root.update()    def update(self, new_decibel: float, max_decibel: float) -> None:        self.gaugedb.set_value(np.around(new_decibel, 1))        self.maxdb_display.set_value(f'{max_decibel:.1f}')        self.led.to_red(on=new_decibel > 85)def main() -> None:    with Meter() as meter:        gui = GUI(meter)        gui.run()if __name__ == '__main__':    main()

Output

Layout

Your layout needs a little love. Since the gauge text is at the bottom, why not put all labels at the bottom? Add some padding for legibility's sake, and add some resize sanity. Unfortunately, in addition to missing variable support,tk_tools widgets seem to have a broken layout behaviour because they ignoresticky resize requests; but oh well:

import tkinter as tkimport numpy as npimport pyaudioimport tk_toolsfrom numpy.polynomial import Polynomialfrom scipy.signal import bilinear, lfilterCHUNKS = [4096, 9600]CHUNK = CHUNKS[1]FORMAT = pyaudio.paInt16CHANNEL = 1RATES = [44100, 48000]RATE = RATES[1]def A_weighting(fs: float) -> tuple[np.ndarray, np.ndarray]:    f1 = 20.598997    f2 = 107.65265    f3 = 737.86223    f4 = 12194.217    a1000 = 1.9997    nums = Polynomial(((2*np.pi * f4)**2 * 10**(a1000 / 20), 0,0,0,0))    dens = (        Polynomial((1, 4*np.pi * f4, (2*np.pi * f4)**2)) *        Polynomial((1, 4*np.pi * f1, (2*np.pi * f1)**2)) *        Polynomial((1, 2*np.pi * f3)) *        Polynomial((1, 2*np.pi * f2))    )    return bilinear(nums.coef, dens.coef, fs)def rms_flat(a: np.ndarray) -> float:    return np.sqrt(a.dot(a) / len(a))class Meter:    def __init__(self) -> None:        self.pa = pyaudio.PyAudio()        self.stream = self.pa.open(            format=FORMAT,            channels=CHANNEL,            rate=RATE,            input=True,            frames_per_buffer=CHUNK,        )        self.numerator, self.denominator = A_weighting(RATE)        self.max_decibel = 0    def __enter__(self) -> 'Meter':        return self    def __exit__(self, exc_type, exc_val, exc_tb) -> None:        self.stream.stop_stream()        self.stream.close()        self.pa.terminate()    def listen(self, offset: int) -> float:        block = self.stream.read(CHUNK)        decoded_block = np.frombuffer(block, dtype=np.int16)        y = lfilter(self.numerator, self.denominator, decoded_block)        new_decibel = 20*np.log10(rms_flat(y)) + offset        self.max_decibel = max(self.max_decibel, new_decibel)        return new_decibelclass GUI:    def __init__(self, meter: Meter) -> None:        self.meter = meter        self.root = root = tk.Tk()        root.title('Decibel Meter')        root.grid()        root.grid_rowconfigure(index=0, weight=1)        root.grid_rowconfigure(index=1, weight=1)        root.grid_columnconfigure(index=0, weight=1)        root.grid_columnconfigure(index=3, weight=1)        root.protocol('WM_DELETE_WINDOW', self.close)        self.app_closed = False        self.gaugedb = tk_tools.RotaryScale(root, max_value=120, unit=' dBA')        # This control does not respect resizing via tk.NSEW.        self.gaugedb.grid(row=0, column=0, rowspan=2, sticky=tk.E)        self.maxdb_display = tk_tools.SevenSegmentDigits(root, digits=3, digit_color='#00ff00', background='black')        self.maxdb_display.grid(row=0, column=1, sticky=tk.S, padx=5)        tk.Label(root, text='Max').grid(row=1, column=1, sticky=tk.N, padx=5)        self.led = tk_tools.Led(root, size=50)        self.led.to_red(on=False)        self.led.grid(row=0, column=2, sticky=tk.S, padx=5)        tk.Label(root, text='Too Loud').grid(row=1, column=2, sticky=tk.N, padx=5)        self.offset = tk.IntVar(root, value=0, name='offset')        spinbox = tk.Spinbox(root, from_=-20, to=20, textvariable=self.offset, state='readonly', width=12)        spinbox.grid(row=0, column=3, sticky=tk.SW, padx=5)        tk.Label(root, text='Calibration (dB)').grid(row=1, column=3, sticky=tk.NW, padx=5)    def close(self) -> None:        self.app_closed = True    def run(self) -> None:        while not self.app_closed:            new_decibel = self.meter.listen(self.offset.get())            self.update(new_decibel, self.meter.max_decibel)            self.root.update()    def update(self, new_decibel: float, max_decibel: float) -> None:        self.gaugedb.set_value(np.around(new_decibel, 1))        self.maxdb_display.set_value(f'{max_decibel:.1f}')        self.led.to_red(on=new_decibel > 85)def main() -> None:    with Meter() as meter:        gui = GUI(meter)        gui.run()if __name__ == '__main__':    main()

• python
• python-3.x
• numpy
• audio
• scipy