            env_inc = _make_narrow_noise(bw, envrate, dur, fs, rise, rng)
            env_inc[env_inc < 0] = 0.
            env_inc = np.convolve(b, env_inc)[:len(t)]
            if k in use_group:
                env = np.sqrt(rho) * env_coh + np.sqrt(1 - rho ** 2) * env_inc