diff --git a/src/ps/aps.rs b/src/ps/aps.rs
index 0bc81d1..b612ead 100644
--- a/src/ps/aps.rs
+++ b/src/ps/aps.rs
@@ -47,13 +47,14 @@ pub enum ApsMode {
     /// where new data is weighted with old data, and old data exponentially
     /// backs off. This mode only makes sense when `tau >> nfft/fs`
     ExponentialWeighting {
-        /// Sampling frequency in [Hz]
+        /// Sampling frequency in [Hz], used for computing IIR filter coefficient.
         fs: Flt,
-        /// Time weighting constant, its inverse is its approximate -3 dB point
-        /// for forgetting old history.
+        /// Time weighting constant, follows convention of Sound Level Meters.
+        /// Means the data is approximately low-pass filtered with a cut-off
+        /// frequency f_c of s/tau ≅ 1 → f_c = (2 * pi * tau)^-1.
         tau: Flt,
     },
-    /// Spectrogram mode. Only returns the latest estimates.
+    /// Spectrogram mode. Only returns the latest estimate(s).
     Spectrogram,
 }
 impl Default for ApsMode {
@@ -119,15 +120,29 @@ impl AvPowerSpectra {
         Ok(overlap_keep)
     }
 
+    /// Resets all state, starting with a clean sleave. After this step, also
+    /// the number of channels can be different on the input.
+    pub fn reset(&mut self) {
+        self.N = 0;
+        self.timebuf.reset();
+        self.cur_est = CPS::zeros((0,0,0));
+    }
     /// Create new averaged power spectra estimator for weighing over the full
     /// amount of data supplied (no exponential spectra weighting) using
-    /// sensible defaults (Hann window, 50% overlap).
+    /// sensible defaults (Hann window, 50% overlap). This is a simpler method
+    /// than [AvPowerSpectra.build]. But use with caution, it might panic on
+    /// invalid nfft values!
     ///
     /// # Args
     ///
     /// * `nfft` - FFT Length
-    pub fn new_simple(nfft: usize) -> Result<AvPowerSpectra> {
-        return AvPowerSpectra::build(nfft, None, None, None);
+    ///
+    /// # Panics
+    ///
+    /// - When nfft is not even, or 0.
+    /// 
+    pub fn new_simple(nfft: usize) -> AvPowerSpectra {
+        AvPowerSpectra::build(nfft, None, None, None).unwrap()
     }
 
     /// Create power spectra estimator which weighs either all data
@@ -147,7 +162,7 @@ impl AvPowerSpectra {
     /// - `nfft` - The discrete Fourier Transform length used in the estimation.
     /// - `windowtype` - Window Type. The window type to use Hann, etc.
     /// - `overlap` - Amount of overlap in
-    /// - `mode` - The mode in which the
+    /// - `mode` - The mode in which the [AvPowerSpectra] runs. See [ApsMode].
     ///
     pub fn build(
         nfft: usize,
@@ -393,7 +408,8 @@ mod test {
             assert!(false, "Should return one value");
         }
         let overlap_keep = AvPowerSpectra::get_overlap_keep(nfft, Overlap::NoOverlap).unwrap();
-        if let ApsResult::OnlyLastResult(v) = aps.compute_last(&timedata_zeros) {
+        if let ApsResult::OnlyLastResult(_) = aps.compute_last(&timedata_zeros) {
+            // Do nothing with it.
         } else {
             assert!(false, "Should return one value");
         }
diff --git a/src/ps/window.rs b/src/ps/window.rs
index 58e922f..ff62082 100644
--- a/src/ps/window.rs
+++ b/src/ps/window.rs
@@ -68,7 +68,8 @@ fn hamming(N: usize) -> Dcol {
     )
 }
 
-/// Window type descriptors. Used for storage
+/// Window type descriptors. Used for computing the actual window with private
+/// functions. See [Window], for the actual window (taper).
 #[derive(Display, Clone, Debug)]
 pub enum WindowType {
     /// Von Hann window