On The Hollow, Cole teams up with German ambient synthesist Matthias Grassow for a collaboration that brings out the absolute finest in both musicians.... Instrumentation herein is primarily synths, flute, singing bowls, with Cole’s harmonic overtone singing and tamboura; guest musicians contribute glass harp, bow chimes, didgeridoo and percussion. In addition, field recordings are used generously to add effects and atmosphere, as on the opener “Spring Dawn” where the sound of a stream, rain, birds, and insects introduce the powerful drones...

“Ululations Through the Hollow” take the drones deeper and darker, closer to the ever-expanding subconscious states where all sounds merge...

Things get more intense and introspective on the appropriately titled “Dark Swirl”, and eventually we end up at “Vanishing Flame”, where a fire slowly introduces Cole’s overtone harmonics and later Grassow’s drones, merging to become one organic breathing cosmic being for its 24 minute duration. “Contemplation” is the only cut here that features vocals by both Cole and Grassow, but an outstanding one it is.

                                           ~ Peter Thelen, Exposé

Faint birdlife and trickling waters are heard beneath the synth-enshrouded terrain of Spring Dawn, where rising/falling vocal emissions spiral above. Lightly shimmering chimes speckle the thrumming entrance to Ululations Through the Hollow; multilayered drones, ranging from throbbing lows to sheening highs...

                         ~ David Opdyke, AmbiEntrance    

...the mixture of human voice, gentle yet somber (and even dark at times) keyboards, and scattered other instruments (flute, singing bowls, tamboura, didgeridoo, glass-harp, bow-chime and up-right) combine with the recordings of insects, water, rain, distant thunder, and other woodland sounds....The centerpiece of the recording is the nearly twenty-four minute "Vanishing Flame," a remarkably slow and evolutionary work with the sound of running water and rain melding seamlessly with drones and Cole's vocal magic....the transitions from phase to phase are patient and deliberate.

I particularly like the opening "Spring Dawn," which is one of the "lightest" songs here, as well as the appropriately titled "Dark Swirl," one of the darker cuts on the album.  The latter is a total immersion into the best kind of deep space music, as inky black smoky drones pour into overtone singing.  This is followed by the delicate "Aspire," on which Mathias brings a fragile sense of beauty to his keyboards.  The music on this album represents one of those rare occasions when two musicians merge their considerable talents into a true symbiotic outcome.  Mathias Grassow and Jim Cole have given us a modern masterpiece.

~ Bill Binkelman, Wind and Wire