Need Help Proofreading (Brief "Frozen Moment" piece)

Had to write this frozen moment piece for my writer's craft class and would really like some feedback or perhaps someone to proof read it.

The city was alive with afternoon commotion. The sounds of everyday life filled the urban air as people rushed to and from, their voices sharp, nearly deafening, in the busy streets. Amidst the crowds of rushing people, an elderly man sat at the opening of a dark, narrow alleyway. His clothes were heavily worn and tattered and a guitar was perched on his thigh, where the material of his blue jeans gaped open to expose his bony knee. Equally bony fingers poked out from the sleeve of his shabby, stained sport coat and pawed awkwardly at the fretboard while his other hand hung over its body, stroking the strings gently. A raspy song poured out of his mouth as he sang along with the off-key tunes of his guitar. People passed him on the sidewalk as he sang with faces of pity, their hands fishing coins from their pockets and depositing them in his ratty guitar case which lay on the ground beside him. Other groups of people walked by without noticing him, their conversations loud and all-consuming as they shoved their way through the crowded streets. One particular man, clad in an expensive looking business suit, strutted down the sidewalk, eyes searched for the source of the off-key song, face twisted in disgust. His disgusted expression, however, loosened and settled on one of guilt as he saw the man's tattered clothing and coin filled guitar case. He slowed and produced a twenty dollar bill from his pocket, stooping to place it gently in the old man's guitar case before standing straight, righting his suit, and walking away quickly.

The old man's head tilted back as he pointed his face to the sky and sang his song to the beating sun. He did not notice the money as it piled up in his discarded case and he did not open his eyes to acknowledge the well dressed man as he passed him by. The bright light illuminated the shadows of his weathered, wrinkled face and exposed ugly scars and spots on his skin. His face contorted like old wrinkled putty as his mouth moved around lyrics which painted fantasies in his mind, even though they could not be heard through the noise of the busy, downtown streets. His cheeks, chin, and upper lip were covered by a thick matted mess of greying brown hair, which brushed roughly against the chapped, splitting skin of his lips as they moved. As his song neared its end, enthusiasm spread across his features and his voice began to overpower the noise of the buzzing city. His crooked fingers clawed forcefully and loudly against the strings, drawing the attention of passers-by. The loud wailing of his voice and the insufferable clanging of his poorly tuned guitar rang out as passion flowed from him, filling the streets with the sound of his song. Then, abruptly, he swung his hand roughly against the strings in conclusion and leaned back against the alley wall behind him. His eyes opened and he scanned the people who had now crowded around him in awe. For one lingering moment, the busy people of the downtown streets stopped to gaze at the man sitting on the corner, singing his song. Slowly, their attention began to wane, and the city once again fell back into its buzzing commotion, hastily moving around the old man as he sat still on the ground, a satisfied smile hung on his wrinkled face.

Thanks for reading!:-D