def synthesize(self, duration, tick_frequency):
        """
        Synthesize periodic "ticks", generated from white noise and an envelope

        Args:
            duration (numpy.timedelta64): The total duration of the sound to be
                synthesized
            tick_frequency (numpy.timedelta64): The frequency of the ticking
                sound
        """
        sr = self.samplerate.samples_per_second
        # create a short, tick sound
        tick = np.random.uniform(low=-1., high=1., size=int(sr * .1))
        tick *= np.linspace(1, 0, len(tick))
        # create silence
        samples = np.zeros(int(sr * (duration / Seconds(1))))
        ticks_per_second = Seconds(1) / tick_frequency
        # introduce periodic ticking sound
        step = int(sr // ticks_per_second)
        for i in range(0, len(samples), step):
            size = len(samples[i:i + len(tick)])
            samples[i:i + len(tick)] += tick[:size]
        return AudioSamples(samples, self.samplerate)