Whistle and Wrong Lyrics: Synthetic Queries Are Not Enough for Real-World Query-by-Melody

People look up a song by humming it, but also by whistling it or singing it with the wrong words. Published query-by-humming systems and benchmarks focus on hums and sung queries, and no public dataset pairs whistles or wrong-lyrics singing with song recordings. We study both query types with a melody-only retrieval system: a key-normalized pitch track embedded by a 5.2M-parameter contour encoder, with a spectral-peak tracker for whistles. First, a physics-grounded generator renders synthetic whistles and nonsense-syllable singing from the vocal melodies of 11,083 songs. Training on them raises top-1 retrieval of held-out synthetic queries against an 11,050-song gallery from 0.180 to 0.251 for whistles and from 0.193 to 0.264 for wrong-lyrics singing, but the gain does not transfer: on the MLEnd test performers the best synthetic-only model gets 210 of 339 real whistles right at top-1, against 214 for the baseline. Second, a closed-set fine-tune on real MLEnd whistles with performer-disjoint splits raises whistle-to-hum top-1 from 0.631 (95% CI 0.581-0.681) to 0.673 (0.622-0.723), on known songs only. Third, two further generations of synthetic queries also fail to transfer: melody-conditioned whistles and la-la singing from a commercial neural music model leave real-whistle top-1 at 0.631, and an open-source pipeline (YingMusic-Singer-Plus singing with partly wrong, mumbled or nonsense lyrics, a DDSP whistle synthesizer, and a melody-error model fitted on real performers) gives at best 0.619 (paired difference -0.012, 95% CI -0.038 to +0.015). Across physics-based, commercial neural and open-source neural synthetic data, nothing transferred to real whistles, which points to collecting real queries as the missing step. Code is public; models and data will be released.