AudioSource.GetSpectrumData failed; Length of the sample buffer must be a power of two between 64 and 8192

Question

In Unity, I have a script that is meant to take audio input from the mic, and get its spectrum data.

When I attach this to a game object and hit 'play', the script correctly gets the loudness of the mic, but gives an error when trying to get the spectrum data. Specifically, it gives this error:

AudioSource.GetSpectrumData failed; Length of the sample buffer must be a power of two between 64 and 8192.

What can I do to resolve this?

My script:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class AudioAnalyzer : MonoBehaviour
{
    string micName;

    AudioSource micAudioSource;

    public float loudness;
    int sampleWindow = 512;

    public float[] spectrum = new float[512];

    void Start()
    {
        micName = Microphone.devices[0];

        micAudioSource = GetComponent<AudioSource>();
        micAudioSource.clip = Microphone.Start(micName, true, 10, AudioSettings.outputSampleRate);
    }

    void Update()
    {
        loudness = GetLoudness();

        SetSpectrum();
    }

    float GetLoudness()
    {
        int clipPosition = Microphone.GetPosition(micName);
        int startPosition = clipPosition - sampleWindow;

        if (startPosition < 0) {
            startPosition = 0;
        }

        float[] waveData = new float[sampleWindow];
        micAudioSource.clip.GetData(waveData, startPosition);

        float totalLoudness = 0f;

        for (int i = 0; i < sampleWindow; i++) {
            totalLoudness += Mathf.Abs(waveData[i]);
        }

        float avgLoudness = totalLoudness / sampleWindow;

        return avgLoudness;
    }

    void SetSpectrum() {
        micAudioSource.GetSpectrumData(spectrum, 0, FFTWindow.Blackman);
    }
}