diff --git a/beat.py b/beat.py
index 7e1d73a..1af0b20 100644
--- a/beat.py
+++ b/beat.py
@@ -169,11 +169,12 @@ class RegularBeatFinder:
     def find_beat(self, fs, ssf_zxings, f_hint=None, debug_fe=False, debug_i=None):
         """Find the optimal beat frequency."""
         act_ibis = np.diff(ssf_zxings)
+        # nice-to: may be interesting to also use as score: the ssf amplitude info at the beats to which we aligned
         # evaluate mean absolute errors for all frequencies
         freqs, freq_errs = self._get_opt_ibi_freq_2(fs, act_ibis, debug_i)
         # bias with f_hint - once we know the beat freq, make it more likely for it to be found everywhere
         if f_hint is not None:
-            nf, f1, f2 = RegularBeatFinder.num_freqs, RegularBeatFinder.range_f2, RegularBeatFinder.range_f1
+            nf, f1, f2 = RegularBeatFinder.num_freqs, RegularBeatFinder.range_f1, RegularBeatFinder.range_f2
             bias = gauss(
                 nf,
                 (f_hint - f1) / (f2 - f1) * nf,
diff --git a/song.py b/song.py
index 017ad78..3b22e36 100644
--- a/song.py
+++ b/song.py
@@ -8,8 +8,9 @@ from sqi import gauss, shift
 class SongBeatDetector:
     SEGMENT_SLICE_LEN_SEC = 8.0  #: slice length for processing (long enough to contain bar structure; short enough for a constant freq. beat placement)
     SSF_REL_THRES = 1.5  #: optimize for slope of error (mae) function over beat frequency
+    NE_THRES = 30.0  #: normalized error threshold for 'good' slices
     def __init__(self): pass
-    def detect(self, fs, sig, debug_fe_idx=None):
+    def detect(self, fs, sig, use_f_hint=True, debug_fe_idx=None):
         self.fs = fs
         #self.sig = sig
 
@@ -31,14 +32,27 @@ class SongBeatDetector:
 
         # we segment on 'guitar' info, but process 'bass' later
 
-        seg_sl = int(SongBeatDetector.SEGMENT_SLICE_LEN_SEC * fsd)
+        if use_f_hint:
+            # initial estimate (without 'f_hint')
+            zds_initial = self._estimate_segments(debug_fe_idx=None)
+            self.zds_initial = zds_initial
+            ifbs_good = np.array([zdd['ne'] < SongBeatDetector.NE_THRES for zdd in zds_initial])
+            fbs = np.array([zdd['fb'] for zdd in zds_initial])[np.where(ifbs_good)[0]]
+            bins, hfreq = np.histogram(fbs)
+            ih = np.argmax(bins)
+            self.f_hint = np.mean((hfreq[ih], hfreq[ih+1]))  # center freq of bin
+        else:
+            self.f_hint = None
+
+        # actual estimate (using 'f_hint' to bias each segment)
+        self.zds = self._estimate_segments(f_hint=self.f_hint, debug_fe_idx=debug_fe_idx)
 
-        self.zds = self._estimate_segments(debug_fe_idx=debug_fe_idx)
         return self.zds
 
     def _estimate_segments(self, f_hint=None, debug_fe_idx=None):
         zds = []
         fsd = self.fsd
+        seg_sl = int(SongBeatDetector.SEGMENT_SLICE_LEN_SEC * fsd)  # segment slice length in 1/fsd units
         # for each segment
         for i in np.arange(self.i_seg.shape[0]-1):
             i1, i2 = self.i_seg[i], self.i_seg[i+1]
@@ -56,17 +70,16 @@ class SongBeatDetector:
                     debug_fe = i1 <= debug_fe_sidx < i2
                 else:
                     debug_fe = False
-                zdd = self._process_slice(j1, j2, m, seg_sl, sig_slice, f_hint=f_hint, debug_fe=debug_fe)
+                zdd = self._process_slice(j1, j2, m, sig_slice, f_hint=f_hint, debug_fe=debug_fe)
                 zds.append(zdd)
 
         return zds
 
-    def _process_slice(self, j1, j2, m, seg_sl, sig_slice, f_hint=None, debug_fe=False):
+    def _process_slice(self, j1, j2, m, sig_slice, f_hint=None, debug_fe=False):
         """
         :param j1: lower index into 'sig_slice'
         :param j2: upper index into 'sig_slice'
         :param m: slice number (used to check if debugging)
-        :param seg_sl: segment slice length in 1/fsd units
         :param debug_fe: show plots for SSF and raw/reg beat placement
         """
         # TODO: C++ impl of SsfZxing._ssf_det_zxings() has diverged.
@@ -75,7 +88,8 @@ class SongBeatDetector:
         # - ?? others ??
         # NOTE: SsfZxing here is always getting short 8-sec slices only (nb. for 'ssf_th' comput.)
 
-        fsd = self.fsd #: reciprocal window step size
+        fsd = self.fsd  # reciprocal window step size
+        seg_sl = int(SongBeatDetector.SEGMENT_SLICE_LEN_SEC * fsd)  # segment slice length in 1/fsd units
 
         SsfZxing.ssf_rel_thres = SongBeatDetector.SSF_REL_THRES
         zd = SsfZxing()